simple teamcity support

Simple Teamcity integration for MergeRequest build status and link on a build.

Algorithm is very simple but it is working for us since 2014/07/15 and everybody happy :-)

Algorithm: get status of the last build in Teamcity for concrete Teamcity.BuildConfiguration_ID and MergeRequest.SourceBranch


Do not write to stdout. Use Rails' logger if you want to log.