allow options to be passed to user-plugins
Merge pull request #14 from taskrabbit/options_for_plugins

allow options to be passed to user-plugins
v0.3.2
test order maters and I don't know why
flatten arguments like JobLock
no need to try/catch in a domain; fix internal error callbacks
test cleanup
update ruby and add example
Merge pull request #15 from taskrabbit/cleanup

Cleanup
v0.3.3
Allows jobLock option.key to be a function.

This can be used to return custom keys that depend on the job. My use
case is to prevent multple jobs of the same type from running, and
ignoring their options.