Issue decription: We configured in our repository that Travis-CI checks will be a mandatory condition for a PR to be merged. The issue is, when a contributor adds a [skip ci] tag into his commit (say, when editing a README), a build is not issued (as expected), but Github is still expecting for a status update from Travis-CI, which blocks the PR from being merged.
Example: https://github.com/vegastrike/Vega-Strike-Engine-Source/pull/163
Expected behavior: When [skip ci] tag is added to the build, either Github shouldn’t expect an update from Travis-CI, or Travis-CI should send a success status to Github to allow the merge.