Merge pull request #125 from mtaylor/rename_assign_button

Renamed 'Assign' button to 'Assign / Unassign'
Version bump
Maintain hostgroup selection after assign host

This patch updates the deployment show page to maintain the selected
HostGroup after a the user selects the "Assign / Unassign" button.
Previous behaviour reset the selected Hostgroup to the first Hostgroup
listed.