Issue #25: Initial implementation of the json file output

This commit just adds the format option to the plugin. In addition, it updates
the README.md to describe the feature. An example of it is below.

This provides initial Fix #25.

-rw-rw-r-- 1 mdesales mdesales  190 Nov 25 14:39 TODO.md
-rw-rw-r-- 1 mdesales mdesales  190 Nov 25 14:42 todos.json
mdesales@ubuntu [11/25/201414:54:40] ~/dev/github-intuit/sp-quality (master *) $ cat docs/todos.json
[
    {
        "file": "index.js",
        "text": "Find a workaround to install https://github.com/badges/shields locally as a module",
        "kind": "FIXME",
        "line": 139
    }
]

*	modified:   README.md
- Adding the documentation on the README about this option.

*	modified:   index.js
- Converting the comment to the json instead of text only.