Fix #97

[2e0byo]

Blindly reverting after git bisect; I've not checked why it was thought that the semantics of ConWebsock had changed.

Test suite passes for websocket. Flaky failure of test_bigfile over serial on my hardware, but unrelated to this commit.

Additionally fixes two bugs in the testsuite:

• uos not os in conftest
• os.getcwd() fails as os not imported, but is equivalent to "." anyhow

Incidentally your testsuite has inspired me to run pytest locally and command behaviour on the hardware as a general workaround for testing being quite hard in uP.

[2e0byo]

bother, didn't mean to edit requirements.txt. Still, as it works with the older version I'll leave it in place for now.

[skorokithakis]

Thanks!