TEST: Bugfix matching available files found by run_tests.py
TEST: Bugfix matching available files found by run_tests.py

The bug manifests as failure to handle the exclusion of test syntax;
e.g., the example command in the help message of run_tests.py fails

  run_tests.py --fast -- -abstract -synth

While not an incorrect behavior, before this commit attempting to run
absent test files led to a cryptic `IndexError: list index out of range`
Now a command like `run_tests.py Caltech` will cause Nose to report
that the module was not found.

tulip-control/tulip-control,necozay/tulip-control,tulip-control/tulip-control,tulip-control/tulip-control,necozay/tulip-control,necozay/tulip-control,necozay/tulip-control,necozay/tulip-control,tulip-control/tulip-control