CMS-3884 Detail View - Version History

- created GetContentVersionsRequest and GetActiveContentVersionsRequest along with responses to fetch data
- created ContentItemVersionsPanel, ContentVersionsTreeGrid, ActiveContentVersionsTreeGrid, AllContentVersionsTreeGrid for displaying results
- also created ContentVersionViewer to be used inside grids
- fixed the TabMenu alignment and layout
- fixed the workspaceService null pointer in NodeServiceImpl.java
Merge pull request #927 from enonic/cms-3884

CMS-3884 Detail View - Version History