Abort with error when patch isn't found

This should fix #98.

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Don't colorize patches

It would be nice to git-colorize these in the future, though.

Signed-off-by: Stephen Celis <stephen@stephencelis.com>
Merge branch 'master' of github.com:stephencelis/ghi