- move tests to root directory
- split tests in different subdirectories
- setup a small package with common test dependencies in /testing/test_soledad
- add tox.ini that will:
  - install the test_soledad package and other test dependencies
  - install soledad common, client, server from the repository
  - run tests contianed in /testing/tests directory using pytest

This commit also removes all oauth code from tests, as we have removed the
u1db dependency (by importing it into the repo and naming it l2db) and don't
neet oauth at all right now.

From this moment on, we embed a fork of u1db called l2db.

This moves the reactor time to the loopingcall period.
This is necessary as the decryption is now deferred to a thread.
The test will exit before the task is executed otherwise.

It was breaking E126 and E202 before

EncryptedSyncTestCase.test_sync_very_large_files is still getting an
excessive amount of memory on very slow machines (specially on old
spinning magnetic disks). This commit checks each doc at a time instead
of getting them all. More refinement is necessary for this test to pass
on any machine.

Pep8 was warning about assignment of lambdas. These lambdas should
be partials