Support multiple repositories

Also closes #3

commit 725de26fe331470f9fe3d17bad4c365ff8772443
Author: Rhys Arkins <rhys@keylocation.sg>
Date:   Tue Jan 10 13:32:07 2017 +0100

    Improve console messages

commit 28ec77634b86ddb7ed8410053d671bad59133058
Author: Rhys Arkins <rhys@keylocation.sg>
Date:   Tue Jan 10 12:25:26 2017 +0100

    Refactor github helper

commit 5cd2cf8eb7049868b0d1bc0d225a6cc490ec3317
Author: Rhys Arkins <rhys@keylocation.sg>
Date:   Tue Jan 10 11:20:27 2017 +0100

    Support multiple repos

commit 52e531c13078e448cecb651b94ce76e24df3d60d
Author: Rhys Arkins <rhys@keylocation.sg>
Date:   Tue Jan 10 11:19:24 2017 +0100

    Hardcode base branch