Supress the AssertionError in printing the result

[msvbhat]

Right now whenever there is a failure in each test case, the result says FAIL and throws exception. That exception looks bit ugly and should be suppressed.

[msvbhat]

From what i could see, this is not possible with python unittest runner (which is being used internally by distaf). The only solution ATM seems to be to override the python unittest assert methods not to throw the exception to the console. But there should be a better solution. If I can somehow make nosetests test runner, then we don't need to worry about it.

I will update again, once I get some solid idea.