Introducing mocked BuildServerBackend client.
Improve unit tests
Merge pull request #2 from devhub-tud/mocked-client

Introducing mocked BuildServerBackend client.
Merge pull request #3 from devhub-tud/improve-testing

Improve unit tests
Disable test which should not yet be in master.
Merge branch 'master' of github.com:devhub-tud/build-server into killing-and-timeouts