Installation struct API call

* jsonschema and model for InstallationStruct added
* post API call handled
* DB migration fixed for adding new tables
* .gitreview added
* licence text added into files
* test app and uwsgi conf for test app added
* import cycles fixed (reproduced on CI only)
* autocommit option removed from DB session

Blueprint: send-anon-usage
Change-Id: If83cb6f86fa96d609da4453ed7417cff996c2019