Added MTAppGroupFilter

$.MTAppGroupFilter();
Add (for PowerCMS) to comment
Add MTAppSnippetHelper and MTAppSortableSnippet
Fix MTAppSnippetHelper
Edit MTAppSnippetHelper and MTAppSortableSnippet
Fix a bug for PowerCMS
Comment out MTAppSnippetHelper and MTAppSortableSnippet
Merge branch 'refs/heads/develop'