Updating client dependencies. Switching to yarn. (#6433)

* Updating client dependancies. Switching to using yarn.

* Updating React

* Moving pure components to using function syntax (performance gains with newer react version)

* Updating client dependancies.

* Ignore .yarninstall

* Enabling pre-lockfile because it's the entire point of using yarn.

* Removing old webpack config

* Moving to new prop-types

* Fixing ESLint Errors

* Updating jest snapshots.

* Cleaning up package.json

webapp/components/get_ios_app/get_ios_app.jsx

@@ -9,60 +9,58 @@ import {Link} from 'react-router';
 import AppStoreButton from 'images/app-store-button.png';
 import IPhone6Mockup from 'images/iphone-6-mockup.png';
 
-export default class GetIosApp extends React.Component {
-    render() {
-        return (
-            <div className='get-app get-ios-app'>
-                <h1 className='get-app__header'>
-                    <FormattedMessage
-                        id='get_app.iosHeader'
-                        defaultMessage='Mattermost works best if you switch to our iPhone app'
-                    />
-                </h1>
-                <hr/>
-                <a
-                    className='get-ios-app__app-store-link'
-                    href={global.window.mm_config.IosAppDownloadLink}
-                    rel='noopener noreferrer'
-                >
-                    <img src={AppStoreButton}/>
-                </a>
-                <img
-                    className='get-app__screenshot'
-                    src={IPhone6Mockup}
+export default function GetIosApp() {
+    return (
+        <div className='get-app get-ios-app'>
+            <h1 className='get-app__header'>
+                <FormattedMessage
+                    id='get_app.iosHeader'
+                    defaultMessage='Mattermost works best if you switch to our iPhone app'
                 />
-                <h2 className='get-ios-app__already-have-it'>
-                    <FormattedMessage
-                        id='get_app.alreadyHaveIt'
-                        defaultMessage='Already have it?'
-                    />
-                </h2>
-                <a
-                    className='btn btn-primary get-ios-app__open-mattermost'
-                    href='mattermost://'
-                >
-                    <FormattedMessage
-                        id='get_app.openMattermost'
-                        defaultMessage='Open Mattermost'
-                    />
-                </a>
-                <span className='get-app__continue-with-browser'>
-                    <FormattedMessage
-                        id='get_app.continueWithBrowser'
-                        defaultMessage='Or {link}'
-                        values={{
-                            link: (
-                                <Link to='/switch_team'>
-                                    <FormattedMessage
-                                        id='get_app.continueWithBrowserLink'
-                                        defaultMessage='continue with browser'
-                                    />
-                                </Link>
-                            )
-                        }}
-                    />
-                </span>
-            </div>
-        );
-    }
+            </h1>
+            <hr/>
+            <a
+                className='get-ios-app__app-store-link'
+                href={global.window.mm_config.IosAppDownloadLink}
+                rel='noopener noreferrer'
+            >
+                <img src={AppStoreButton}/>
+            </a>
+            <img
+                className='get-app__screenshot'
+                src={IPhone6Mockup}
+            />
+            <h2 className='get-ios-app__already-have-it'>
+                <FormattedMessage
+                    id='get_app.alreadyHaveIt'
+                    defaultMessage='Already have it?'
+                />
+            </h2>
+            <a
+                className='btn btn-primary get-ios-app__open-mattermost'
+                href='mattermost://'
+            >
+                <FormattedMessage
+                    id='get_app.openMattermost'
+                    defaultMessage='Open Mattermost'
+                />
+            </a>
+            <span className='get-app__continue-with-browser'>
+                <FormattedMessage
+                    id='get_app.continueWithBrowser'
+                    defaultMessage='Or {link}'
+                    values={{
+                        link: (
+                            <Link to='/switch_team'>
+                                <FormattedMessage
+                                    id='get_app.continueWithBrowserLink'
+                                    defaultMessage='continue with browser'
+                                />
+                            </Link>
+                        )
+                    }}
+                />
+            </span>
+        </div>
+    );
 }