Add configurable parameters for metric interval and event TTL
Prioritize critical thresholds

By reversing the order of checks, users can
specify thresholds which can go from ok to
critical directly if desired.
Merge pull request #2 from pyr/feature-prioritize-critical

Prioritize critical thresholds
Merge pull request #1 from firewing1/master

Add configurable parameters for metric interval and event TTL