kick-job command
kick-job requires beanstalkd >= v1.8
Merge pull request #24 from lyxint/kick-job

Merge implementation and documentation of the kick-job command.
Rename Job.kick_job to Job.kick
Fix doctest for Job.kick
Minor documentation cleanups
Also run "wip-travisci" branch via Travis CI
Test with custom-built beanstalkd 1.8 on Travis CI

Our testsuite tests features only available with beanstalkd 1.8+. To
make this dependency explicit, we now build beanstalkd from source on
Travis CI instead of relying on on distro-provided packages.