Increased username max length

web/react/components/signup_user_complete.jsx

@@ -303,7 +303,7 @@ class SignupUserComplete extends React.Component {
                                     ref='name'
                                     className='form-control'
                                     placeholder=''
-                                    maxLength='128'
+                                    maxLength={Constants.MAX_USERNAME_LENGTH}
                                     spellCheck='false'
                                 />
                                 {nameError}

web/react/components/team_signup_username_page.jsx

@@ -115,7 +115,7 @@ class TeamSignupUsernamePage extends React.Component {
                                         className='form-control'
                                         placeholder=''
                                         defaultValue={this.props.state.user.username}
-                                        maxLength='128'
+                                        maxLength={Constants.MAX_USERNAME_LENGTH}
                                         spellCheck='false'
                                     />
                                     {nameHelpText}

web/react/components/user_settings/user_settings_general.jsx

@@ -514,6 +514,7 @@ class UserSettingsGeneralTab extends React.Component {
                     <label className='col-sm-5 control-label'>{usernameLabel}</label>
                     <div className='col-sm-7'>
                         <input
+                            maxLength={Constants.MAX_USERNAME_LENGTH}
                             className='form-control'
                             type='text'
                             onChange={this.updateUsername}

web/react/utils/constants.jsx

@@ -461,7 +461,7 @@ export default {
     },
     OVERLAY_TIME_DELAY: 400,
     MIN_USERNAME_LENGTH: 3,
-    MAX_USERNAME_LENGTH: 15,
+    MAX_USERNAME_LENGTH: 64,
     MIN_PASSWORD_LENGTH: 5,
     MAX_PASSWORD_LENGTH: 50,
     TIME_SINCE_UPDATE_INTERVAL: 30000