In task manager and task manager test rest apis when a task or module
which does not exist is requested, we get Internal Server Error.
In such cases, wrap thrown exceptions in bad_param_exception
to respond with Bad Request code.
Modify test accordingly.
Task manager api will be used in many tests. Thus, to make it easier
api calls to task manager are wrapped into functions in task_manager_utils.py.
Some helpers that may be reused in other tests are moved there too.
