avatars: Use more reliable LastWriteTime to determine whether the avatar needs refetching
Added new icon for Mac Yosemite+
Merge pull request #1586 from snwh/master

Added new icon for Mac Yosemite+
mac ui: Integrate new Yosemite folder icon. Closes #1585
Update Authors.txt
mac bubbles: Clean up
Update Authors.txt
Merge pull request #1587 from BarryThePenguin/patch-1

Update Authors.txt
Squirrel integration

- changed to .NET 4.5
- added nuget
- added nuspec file for releases
- Created basic events for UpdateManager
- Updater runs at the end of UIHasLoaded
- SparkleAbout now gets updates from the UpdateManager
- SparkleInviteOpener now manages protocolhandler installation and maintenance
- SparkleInviteOpener now handles github and sourcetree protocols, fixes #1570 for windows
- Discovered HKEY_CURRENT_USER\Software\Classes merges with HKEY_CLASSES_ROOT so no need to elevate privileges to add protocol handlers
- Close SparkleShare on Update or Uninstall
- Preparation for squirrel update