Various small fixes and comments arroud "UpdateStatus"

 - Use more of the available source control icons
 - Fix the special case of a newly content file added but not saved
 - Added unmerged "Conflict" cases
 - Fix for the Source Control status tooltip
 - Readme (c) 2014
Path to Git binary is now configurable
UE4 Git Plugin Binary v0.0

 - usable, but it does only shows icon above content assets