Cron predictor conformance test.

Quartz doesn't support "standard" cron syntax (as described in
crontab(5)[1]) and deviates [2] in a lot of ways that would lock us into
it. Some of the ways it varies include:
  * '00' is not a valid minute
  * day-of-week is 1-indexed instead of 0-indexed
  * it supports a seconds field, which is an unrealistic constraint for aurora to deliver
  * the common "* * * * *" pattern is invalid

Rather than adopt Quartz's syntax I propose introducing a translation
layer that will allow users to write in the more familiar crontab
syntax. This change adds test data that can be used as a conformance
test - a valid CronPredictor implementation must both accept the same
syntax and make the same predictions as those referenced here. In a
future review I will introduce a Quartz cron subsystem that passes this
test.

[1] http://unixhelp.ed.ac.uk/CGI/man-cgi?crontab+5
[2] http://quartz-scheduler.org/documentation/quartz-2.2.x/tutorials/tutorial-lesson-06

Testing Done:
./gradlew build

Bugs closed: AURORA-132

Reviewed at https://reviews.apache.org/r/18149/