Merge pull request #170 from jaehnri/master

Add omitempty to Preferences theme

Author: inkel

Diff for: preferences.go

@@ -20,7 +20,7 @@ type QueryHistoryPreference struct {
 
 // Preferences represents Grafana preferences.
 type Preferences struct {
-	Theme            string                 `json:"theme"`
+	Theme            string                 `json:"theme,omitempty"`
 	HomeDashboardID  int64                  `json:"homeDashboardId,omitempty"`
 	HomeDashboardUID string                 `json:"homeDashboardUID,omitempty"`
 	Timezone         string                 `json:"timezone,omitempty"`