(#260) Correcing AppVeyor Support for Pull Requests

- As per discussion with @nulltoken, implemented a fix for AppVeyor where if the commit sha is not present of any detected local branches, check out a new branch using the sha as the pointer
(#260) Adding output for GenerateSetParameterMessage

- As per suggestion here:

https://github.com/Particular/GitVersion/issues/260#issuecomment-56985673
(#260) Favour local branches over remote ones

- Updated with suggestion from @nulltoken
- https://github.com/Particular/GitVersion/pull/262#discussion_r18103422
Merge pull request #262 from gep13/AppVeyorFixes

Correcting AppVeyor Support for Pull Requests