Refactored to support https connections.

* Renamed variable HUBOT_TEAMCITY_HOSTNAME to HUBOT_TEAMCITY_URL
* Expected notation of HUBOT_TEAMCITY_URL is scheme://host:port (for example https://teamcity.example.com)
Added author name. :)
Keep old variable HUBOT_TEAMCITY_HOSTNAME and introduce a new
HUBOT_TEAMCITY_SCHEME which holds the scheme and defaults to http.

The base url is created from "#{scheme}://#{hostname}".
Merge pull request #853 from jan0sch/master

Refactored teamcity.coffee to support https connections too.