The change adds no new functionality and aims to move flags definitions
to subpackages that are using them. This should improve readability
of the main function.
* Initial rules evaluation support.
Rules are now store alerts state in private field `alerts`. Every evaluation updates
the alerts and state. Every unique metric received from datastore represents a unique alert,
uniqueness is guaranteed by hashing ordered labelset.
* merge with master
* cleanup
* support endAt parameter as 3*evaluationInterval for active alerts
* make golint happy
