First pass at adding a jitter to schedulers. Move Validator to config_utils.
Update scheduler_parse interfaces to take a ConfigGenericSchedule.
Add jitter to constant scheduler, and some test cleanup.
Add jitter to general scheduler.
Update scheduler docs, Resolves #136
Cleanup from code review.
Add docs about hourly alias for interval scheduler.
Merge branch 'release_0.6.1' of github.com:Yelp/Tron into 136_scheduler_jitter
Merge branch 'release_0.6.1' of github.com:Yelp/Tron into 136_scheduler_jitter
Merge branch '136_scheduler_jitter' of github.com:dnephin/Tron into 136_scheduler_jitter
Merge pull request #213 from dnephin/136_scheduler_jitter

scheduler jitter