test for 'equivalency' with JSLint

[eliasmalik]

Write a test that checks that code that fails the JSLint (with default settings) also fails our eslint config.

I put equivalency in quotes because we may decide that there is a good reason to break from a specific aspect of the good parts, in which case the equivalency test can be weakened, but that needs to be explicitly and well justified in an issue.

[jrans]

I think from current setup proposed in #191 we can make sure all passing fixtures in our test runner also pass jslint, using https://github.com/douglascrockford/JSLint/blob/master/jslint.js with abiility to add exceptions if so desire. node-jslint can help this process.

This can be a preliminary measure to be improved. We may therefore want to provide passing cases for ignored rules.

We also obviously need all jslints failing tests to fail ours if we can find their test fixtures