fix "inactive" state color of "Build Up" button in Currikulum Builder

Guillaume:

Is there any way we can easily fix the "Inactive" state of the "Build Up" button in the CB's TOC?

Look at it here:

http://next.dev.curriki.org/xwiki/bin/view/GWT/Editor?xpage=plain&page=Coll_Group_CurrikiLeadersGroup.SampleCourse&mode=edit

And then click between the top level collection and one of the source assets and see how the button appearance changes from Active to Inactive.

Preferably the button would go away altogether when inactive. If we can't do that with styling, please make it follow correct button styling here, as in:

http://www.curriki.org/xwiki/bin/view/Project/Basic+Buttons

Not a high priority.