Feature to disable TestRules when the test class being ran has been
launched in debug mode.

This feature is immediately useful with @Timeouts by disabling them
during debugging allowing developers time to debug at their leisure
without the test terminating abruptly.

Timeouts or time sensitive logic in the code under test is not handled
by this feature and may make this unuseful in some circumstances.

The important benefit of this feature is that you can suspend rules
without any making any modifications to your test class to remove them
during debugging. Anecdotally removing timeouts for debug purposes often
results in developers forgetting to restore them (including myself!).
Merge pull request #956 from kay/disable_on_debug

TestRule to disable specific other TestRules when debugging without modification to the test class