Get dashboard's branch name using multi thread
Cleaning code
Get dashboard's branch name using AsyncLoader
Merge branch 'pr/n2015_emanuelhp'

Conflicts:
	GitUI/CommandsDialogs/BrowseDialog/DashboardControl/DashboardItem.cs
Cancel dashboard's branch name load on hide or dispose
Removed unused using
Merge branch 'pr/n2028_emanuelhp'

Conflicts:
	GitUI/CommandsDialogs/BrowseDialog/DashboardControl/DashboardItem.cs