Don't require a build step in node.js.

Instead, add a main module that creates a new vm context, then evaluates the sources files in it one by one and exports weknowhow.expect from it.
test/common: Use /index instead of the built /lib/unexpected.

This makes regular mocha work, although it currently relies on "common" being asciibetically < "unexpected.spec.js"
Removed unexpected-es4-compatible.js from index as node is es5 compatible
Merge pull request #30 from sunesimonsen/eliminateBuildStepForNodeJsAndMocha

Eliminate build step for node js and mocha