Remove redundant Github api connections, when repository is not Github

Tiny commit that actually does two things:

1. Ensures that github-specific status api requests are not made, when the repository is not github, remembering that, host of github does is not always: github.com - That's why settings.GitHubDomain is used. 

2. Defer functions in go are LIFO, therefore in case of need to recover, last defined defer (updateGitHubStatus) would take place, before the one that does recovery and changes the build status into error. For convenience, those 2 defers, were unified.