This 0.10 release adds an significant improvement when fetching
tests of a build. Now there's no need to go through Build's
testruns in order to get tests, it can be done directly just by
calling `build.tests()`. It's supposed to be much quicker than legacy
code.
Complete list of changes going in:
* core: models: add tests endpoint to build
* core: models: do not crash in str() if attribute is missing
* core: models: add missing url attribute
* rename redundant json: tuxbuild_json to tuxbuild only
* squad_client: commands: submit: metadata: allow more types
* squad_client: commands: submit: metadata: update error message