Make toobusy.max_lag a configuration parameter.
Make TOOBUSY_MAX_LAG be automatically converted to an int.
Make TOOBUSY_MAX_LAG <= 0 disable node-toobusy entirely.
Disable node-toobusy entirely under travis.
Merge pull request #251 from mozilla/rfk/max-lag-config

Configurable max_lag for dev-vs-prod