Add helper for modules written in bash

Adds bash helper functions for ansible bash modules to:
- Automatically parse the module's arguments directly into environment variables.
- Capture stdout/stderr output and return the output as JSON.
- Intercept script errors and return a meaningful messages to ansible when they occur.
- Build structured JSON responses.
- Assist in debugging.

The entire process is described in more details in the included doc, sample and helper module. This pull request is designed to be implemented at the same time or after my other pull request 'Add check mode support to non-python modules'.

Please feel free to make any suggestions as how to make this contribution better and easier for you to review. Thanks!