Bump version to 2.0.4-pre
Back off when Handshake gets null action
Merge branch 'fix_null_handshake' into r2.0.4
Clean up Pusher integration tests
Update SockJS to disable raising INVALID_STATE_ERR
Bump version to 2.0.4
Update Changelog for version 2.0.4
Add ruby-hmac to Gemfile
Merge branch 'r2.0.4'