stomp-client refactoring for more stability and transparency

We detected some dead loops using this client in our project, so we started to remove them.
- Extracted some classes in order get better testabillity.
- Fixed travis-ci config.
- Increase code coverage.
- Removed automatic reconnect in background, this might lead to unexpected results.
- Removed sslTests (Yes, they don't depend on this stomp client, it's php only!)
- Removed stubbed tests, they didn't work at all
merge jh pull request cs changes
Merge branch 'feature/rewrite-client' into issues/1-deadloop-on-connection-exception