Add grep functionality

This PR adds `grep` and `listTests` commands to Intern. `grep` allows tests to be filtered by test ID. `listTests` lists all the tests that Intern will run, post filtering if `grep` is used. `grep` works from the command line and may be set in the test config file. `listTests` only works from the command line. See #123.
This try/catch has several issues:

1. `e` violates style guide
2. console log messages outside reporters is verboten
3. does nothing except log and rethrow