Use HoundCI instead of rubocop

HoundCI is basically rubocop as a service. Excellent idea, let's try it
out.

* You can configure it with a `.hound.yml` that is the normal rubocop
  configuration file.
* It will comment on the pull request – that's exactly what we want!

I removed rubocop, because everything we do on the Repo is done via a
pull request. This is part of the review process, and doesn't need to be
done on the local machine.
Merge pull request #105 from triAGENS/the-hound

Use HoundCI instead of rubocop
Add bindVars to allowed keys for cursor path

Added bindVars to ALLOWED_KEYS_FOR_PATH so the Query#prepare_request
method does not end up stripping out bound variables.
Adjust hound config
Added @sleepycat's example for bind variables to the execute doc
Merge pull request #109 from triAGENS/sleepycat-bindvars

Add bindVars to allowed keys for cursor path [Reviewed]
Added @sleepycat to the contributors
Added Shield.io Badge for Code Coverage on CodeClimate