Add an alias to run_tests that runs all the tests that use tor
From https://trac.torproject.org/projects/tor/ticket/31554#comment:2
Please add an alias to run_tests.py that runs all the tests that use a local tor binary. Maybe it could be called RUN_TOR_TESTS?
We want to use this alias in make test-stem and the Travis stem job. Using a list of tests is fragile.