PLT-2992 Added the ability to use different themes for each team (#3411)

* Cleaned up user_settings_theme.jsx and import_theme_modal.jsx

* Made ImportThemeModal use a callback to return the theme to the user settings modal instead of saving it directly

* Moved user theme from model to preferences

* Added serverside API to delete preferences TODO update package with client stuff

* Changed constants.jsx so that Preferences and ActionTypes can be imported on their own

* Updated ThemeProps migration code to properly rename solarized code themes

* Fixed warnings thrown by AppDispatcher

* Added clientside UI to support team-specific themes

* Removed debugging code from test

* Fixed setting a user's theme when they haven't set their theme before

webapp/dispatcher/app_dispatcher.jsx

@@ -9,7 +9,7 @@ const PayloadSources = Constants.PayloadSources;
 const AppDispatcher = Object.assign(new Flux.Dispatcher(), {
     handleServerAction: function performServerAction(action) {
         if (!action.type) {
-            console.warning('handleServerAction called with undefined action type'); // eslint-disable-line no-console
+            console.warn('handleServerAction called with undefined action type'); // eslint-disable-line no-console
         }
 
         var payload = {
@@ -21,7 +21,7 @@ const AppDispatcher = Object.assign(new Flux.Dispatcher(), {
 
     handleViewAction: function performViewAction(action) {
         if (!action.type) {
-            console.warning('handleViewAction called with undefined action type'); // eslint-disable-line no-console
+            console.warn('handleViewAction called with undefined action type'); // eslint-disable-line no-console
         }
 
         var payload = {