Add go argsparser package

This package converts a command line string into a slice of its
arguments. It is necessary for the task wrapper we're writing which
converts gearman payloads to command line arguments for a process.

It's a bit hacky, but it's the best solution we could come up with.
Merge pull request #10 from Clever/parse-command-line-args

Add go argsparser package
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 comments

Changes the name of the directory and cleans up the way we handle
buffers