Add feature to set test iteration count from command line
Created by: bjackman
This is a kludge, but I think doing this properly basically requires implementing our own Nose test runner, or even our own test-running framework entire. In the short term we really need this feature.
nosetests doesn't provide a way for the user to pass command-line arguments to the test. To get around this, this commit adds a parameter to lisa-test that sets an environment variable, which LisaTest then reads to set or override the iterations count.
This will go pretty nicely with https://github.com/ARM-software/lisa/pull/348 but they are technically independent.