Gollum now uses some of the .NET 4.5 features (async / await)

Gollum now uses some of the .NET 4.5 features (async / await). Fixed
bugs are now parsed better from the commit message. Fixed some other
issues and improved exception handling.

Resolves #1 
Resolves #5 
Resolves #6 
Resolves #7 
Resolves #8