Fix a URL typo in the gemspec and post_install_message
Merge pull request #86 from tedpennings/patch-1

fix a URL typo in the gemspec and post_install_message
list Ted as a contributor
release 3.0.1
use Rufus::Scheduler::NotRunningError

when scheduling/joining against a down scheduler

closes gh-85
3.0.2 pre
do not start work_threads unnecessarily

thanks Gatis Tomsons @gacha

next step: drop vacant work_threads after a while

closes gh-84
fix the start_work_thread conditions

start work thread
  if vacant threads - queued jobs < 1 and
     cur threads < max threads

closes gh-84
fix scheduler_spec for Ruby 1.8.7
adapt specs to JRuby
default :max_work_threads to 28
release 3.0.2
3.0.3 pre
rename #consider_lockfile to #lock

and extract #unlock

for gh-76
introduce ZookeptScheduler example

for gh-76
update changelog and credits
add readme doc about cron L and sun#1

closes gh-88
simplify Job#callback
implement Scheduler#down?
add #confirm_lock callback for gh-76