Provide git version override check reminder

If failing the check, provide a useful note about how to override that check.
When I'm running in a cygwin environment everything seems to work, but I'm constantly forgetting to set this check.  I then have to look this setting up. Putting in the error msg is more human friendly.

Hope this helps the next person in my situation.
Merge pull request #416 from codingtwinky/master

Adding '--version' and exit on invalid option. fix #413
Merge pull request #414 from mattkatz/master

Provide git version override check reminder
Show warning in UI for bad git versions. Fixes #406
Better use of window title
Don't disconnect on bad responses from backend