Import handleAllFailures and failureToString from ooni.errors
Test and implement TasksWithTimeout

Do some refactoring of the unittesting logic
add processTest to NetTest class

ripped out of runner.py and needs testing
Add tests for NetTest

Test loading NetTestCase with required options and verify that
the appropriate exceptions are raised.
Implement and unittest code for tasks that timeout
Refactoring of NetTestCase and NetTest with partial unittesting
Unittesting for MeasurementManager
Basic unittest for representing scapy packets
(cherry picked from commit 442a4a3aa716bfcc3f8f2cd2e249dc000f991950)
Merge branch 'test_nettest' into taskManager

* test_nettest:
  Refactoring of NetTestCase and NetTest with partial unittesting
  Add tests for NetTest
  add processTest to NetTest class