Changed the way Create New Change Set works on the Synchronize page: the command is now active (in the context menu) and functional for children of the Uncommitted group, not just ON the Uncommitted group.

Was already merged in Bitbucket before import, marked as merged by the import user

I consider this a minor modification: it does not change the previous behavior but lifts a restriction that the old behavior had. I constantly use the Synchronize perspective and need to group changesets just as constantly. Having to lose the current selection just so I could create a new changeset was an annoyance. This commit changes that.