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

store/sql_preference_store_test.go

@@ -193,7 +193,7 @@ func TestPreferenceGetAll(t *testing.T) {
 	}
 }
 
-func TestPreferenceDelete(t *testing.T) {
+func TestPreferenceDeleteByUser(t *testing.T) {
 	Setup()
 
 	userId := model.NewId()
@@ -367,3 +367,28 @@ func TestDeleteUnusedFeatures(t *testing.T) {
 		t.Fatalf("Found %d features with value 'true', expected to find at least %d features", val, 2)
 	}
 }
+
+func TestPreferenceDelete(t *testing.T) {
+	Setup()
+
+	preference := model.Preference{
+		UserId:   model.NewId(),
+		Category: model.PREFERENCE_CATEGORY_DIRECT_CHANNEL_SHOW,
+		Name:     model.NewId(),
+		Value:    "value1a",
+	}
+
+	Must(store.Preference().Save(&model.Preferences{preference}))
+
+	if prefs := Must(store.Preference().GetAll(preference.UserId)).(model.Preferences); len([]model.Preference(prefs)) != 1 {
+		t.Fatal("should've returned 1 preference")
+	}
+
+	if result := <-store.Preference().Delete(preference.UserId, preference.Category, preference.Name); result.Err != nil {
+		t.Fatal(result.Err)
+	}
+
+	if prefs := Must(store.Preference().GetAll(preference.UserId)).(model.Preferences); len([]model.Preference(prefs)) != 0 {
+		t.Fatal("should've returned no preferences")
+	}
+}