Collapsing lib/resque_scheduler into lib/resque/scheduler

plus oodles of other changes related to the move, wheeeee!
Extracting some of Resque::Scheduler's functionality into modules

although this is admittedly not an awesome solution.  Needs more work.
Updating ROADMAP post-rebase
Correcting the forward-porting of #365

as it was (whoopsie!) lost in a rebase.
TRIVIAL removing some extra blank lines
Extracting helpers and server methods into modules

both for complexity reasons and so that RuboCop can properly analyze the
methods.
Breaking up the `#find_job` helper method a bit
Breaking up some complex methods in cli, collapsing MUTE/QUIET -> QUIET
Extracting runtime env bits into separate class
Merge remote-tracking branch 'upstream/master' into api-cleanup
Splitting the resque extension's methods up a bit
Merge remote-tracking branch 'upstream/master' into api-cleanup

Conflicts:
	.rubocop.yml
	lib/resque_scheduler.rb
	lib/resque_scheduler/server.rb
	test/scheduler_task_test.rb
Trying to correct JRuby explosion
Switching to kramdown to make JRuby happy
Merge pull request #360 from meatballhat/api-cleanup

API cleanup step 0