Remove env vars dependencies and add mock for unit tests

now you need to specify env vars to be able to run unit tests. also some of unit tests (TestApi.test_api_object) trying to make real requests to the api. all requests should be mocked.

[JanrainMicah]

Reworked the tests to use mocks. Pending review and release of 0.5.0 branch.

@JanrainMicah cool. thank you.
ref #42