Merge pull request #4 from magefree/master

update code
Add UI for background image selection - selection, random, default
Add UI for background image selection - selection, random, default
Merge pull request #5 from magefree/master

update master code
Combine ThemePluginImpl into Mage Client project to avoid cycling dependency.
fix a bug of package importation that cause code not be able to compiled
update and adjustment
Merge pull request #243 from Noahsark/fab2759579276909b534de603feb01f50d326d37

Add UI to set background, fix a little bugs, combine theme plugins to client project to avoid cycling dependency