Support short date format for git-blame
Support short date format for git-blame

Setting git-blame's date format to 'short' caused the syntax regex to 
no longer match. This change marks the time and timezone as optional.

This should support both the default 'iso' format, and 'short'. The
other formats (relative, default, rfc and local) are left unsupported.

(Yes. Git blame has a date format called "default", that is not the 
default format. Go figure)
sunnyagain/sublime-text-git,kemayo/sublime-text-git