added support for pluggable backends
redesigned pluggable backends
reduced latency with notifications
removed notifications again
added list_jobs method to backends
added basic support for non-blocking results
added wait_for method to Minion
added -L and -S options to job command
limit job list to 100 by default
removed support for task results again
fixed typo in Changes file
connect workers and jobs
added reset method to Minion
small optimizations
removed reset methods again
bring back reset methods

This reverts commit 717a801a0b7706013cf173eb9c21db923bc86d6c.
bump version
changed a few return values in Minion::Backend::Mango
use slightly different errors
added priority example