Teamcity8 support & bug fixes

Series of patches that add methods for TC8 API and some small bug fix
The API is not backwards compatible.
Per https://confluence.jetbrains.com/display/TCD8/REST+API:
> Since TeamCity 8.1 Create a new build configuration with all settings: 
> POST http://teamcity:8111/httpAuth/app/rest/buildTypes. The XML/JSON posted is the same as retrieved by GET request. (Note that /app/rest/project/XXX/buildTypes still uses previous version notation and accepts another entity.)