Fix false positives on errors with different messages.

[kurtcorbett]

This PR:

• Sets up mocha and refactors tests in src/specs/test.spec.js to run with either mocha or Jest. This was done to ensure that we can verify that our functional tests work properly with either framework. It could be part of the CI to run both sets of tests.
• Adds regression test and addresses the bug in node's assert.deepEqual where all Errors are considered equal. This is a known and accepted issue as described here Comparing errors through deepEqual nodejs/node#3122

Concerns:

• The modified deepEqual check on Errors is naive, creating two "error" objects with a message and name property and comparing them. I'm concerned about browser compatibility with this. Each browser has different property names on Errors and we could run into problems if someone is testing this with jasmine or some other client side testing framework. We may consider creating a function to normalize error properties across the different browsers and node.

[kurtcorbett]

Added changes per @orourkedd suggestions.

[orourkedd]

Great idea of using the deepEqual and running the tests with both runners.

[kurtcorbett]

We could consider adding Jasmine to ensure client side behavior consistency, possibly across multiple (headless) browsers. It adds overhead to the project, but it'd be nice to be sure that we are covering all likely environments.