Add mock job type for use by other tests

While writing a new worker I noticed that I was duplicating this same
mock job code, so I've factored that out so other workers can use it
too.
Add support for READMEs into the makefile
Clean up language
Merge pull request #7 from Clever/factor-out-mock-job

Factor out mock job
Worker wrapper package

This change defines the package that will be used by the worker wrapper
program. It implements the interface defines in the standalone interface
spec for the wrapper process.

It tests the library with a bunch of simple scripts that exercise each
of the components of the interface.
Code review feedback
Improve some comments
Stream stdout to gearman
Code review comments
Change the way we handle the data fields