Compatibility with Mongoid 4.x and Delayed Job 4.x.
Merge pull request #43 from dblock/mongoid-4x

Compatibility with Mongoid 4.0 and DJ 4.0.
Test against Ruby 2.1.0 and head
Test against JRuby
Test against Rubinius
Show all errors by default
Update to latest RSpec syntax
Added @brixen as a collaborator, who will ensure builds pass on Rubinius