PLT-1800 Load server side locale from the config.json (#3076)

* PLT-1800 Load server side locale from the config.json

* Add support for locales with country specifics

webapp/package.json

@@ -17,8 +17,8 @@
     "jquery": "2.2.3",
     "keymirror": "0.1.1",
     "marked": "mattermost/marked#43e7e590944ea308a4d36f21917118d51a261e74",
-    "mattermost": "mattermost/mattermost-javascript#master",
     "match-at": "0.1.0",
+    "mattermost": "mattermost/mattermost-javascript#master",
     "object-assign": "4.1.0",
     "perfect-scrollbar": "0.6.11",
     "react": "15.0.2",
@@ -26,8 +26,9 @@
     "react-bootstrap": "0.29.3",
     "react-custom-scrollbars": "4.0.0-beta.1",
     "react-dom": "15.0.2",
-    "react-intl": "2.0.0-rc-1",
+    "react-intl": "2.1.2",
     "react-router": "2.4.0",
+    "react-select": "1.0.0-beta13",
     "react-textarea-autosize": "4.0.1",
     "superagent": "1.8.3",
     "twemoji": "2.0.5",