Devrel 332 refactor tests

[kylenstone]

My first PR at Frame.io so I'm saving this as a Draft for now. Few things to point out:

• Removed the run_test() function at the end of integration.py (I also moved this file) because pytest will run the tests automatically. @jhodges10 it's possible this was actually needed for CircleCI so I wanted your eyes on it.
• I rewrote the frameioclient fixture as setup_client which seems like a better fixture name for actual use in following tests. I modified the other tests to use it.
• The new test I added specifies a new file upload path single_file_upload, I didn't want to re-use the upload path from the existing test because it was doing so much work already.
  In a later PR, we should figure out a better setup and teardown lifecycle
• All of this should be 2.7 compliant but please double-check me on that.

[jhodges10]

If merged, this would definitely break the way CircleCI is setup to test currently so once you get write access to the repo - we should talk through it and get you setup on CircleCI.

As for 2.7 compliance - that's the beauty of the automated tests that run across multiple python versions! If it doesn't pass, you'll get a warning and it won't be allowed to merge.

[kylenstone]

Thanks for the feedback, back to drafts until sorted

[jhodges10]

@kylenstone one more thing that needs to be updated is the Circle CI config so that it can find the newly re-named integration test file.

[jhodges10]

@kylenstone, now that I've got the integration test in a good place w/ xxhash verification working correctly and passing most of the time - I'd love to come back to this PR and get your improvements merged in!