add a bunch of tests for the client

client/djrandom_client/test/__init__.py

client/djrandom_client/test/test_client.py

client/djrandom_client/test/test_filescan.py

client/djrandom_client/test/test_throttle.py

client/djrandom_client/test/test_upload.py

client/djrandom_client/test/test_utils.py