Code for running yaml tests

[MalinAhlberg]

(depends on #34)

Commits:

• f45fb6c Run yaml tests, skip all python tests
• e9d27a0 Remove unused code, add newlines etc.

To run: python beacon_api_tester.py --test tests/test-v101-counts.yaml

Note that we do not need to read the data field from the yaml here, as all data should have been loaded into the beacon's database earlier (by external tools).

TODOs:

• The yaml-files should be validated at some point, so that we can assume that all necessary information are there when we run the tests.
• The unittests for the api-tester need to be updated.