Add secret support to PubSubHubbub subscribe
Stub requests for PubSub subscription tests.
Correct step reference

Step 9 redirects readers back to step 3, creating a topic branch, when it should be suggesting that they add specs which is step 4.
Merge pull request #394 from slant/patch-1

Correct step reference
Add instructions for skipping CI builds to CONTRIBUTING

[ci-skip]
Merge pull request #390 from joeyw/pshb-secret-support

Wrap up #333
Update travis config for Rubygems bug

travis-ci/travis-ci/issues#1793