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

Do some refactoring of the unittesting logic
Implement and unittest code for tasks that timeout
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
Move parseNetTestOptions to oonicli
Add NetTestCase option validation

Options that are passed to the NetTest constructor must be valid
options defined in the NetTestCase UsageOptions with optParameters.

Also handle the case where inputFile is *not* a required option and not
supplied gracefully.
Add tests for missing required options and invalid options