Simplify and use node-localstorage

This pull request removes the custom implementation of `localStorage` which was not a full implementation anyway, and replaces it with https://github.com/lmaccherone/node-localstorage. 

This module properly defines quotas and other aspects of the API, with more extensive testing also.

I left the fixtures as they were, but moved the data to `fixtures.json`.
Another change was away from the non-standard `Makefile` approach, and instead, just the use of `testling` which doesn't require multiple steps for testing, and readily works with mocha without `mochify`.
It also readily integrates with the testling module on GitHub if necessary.