First Draft - Engine Rewrite to support client side mocha.js.
"fs.existsSync" takes priority over "path.existsSync"
Change SeleniumDriver and EngineManager to to not read files since the engines now do that themselves.
Wrap exported functions with execution code.
Error Manager Refactoring

The error check logic should be distributed to other classes.
Fix callback issue

callback should be accessed as self.callback in error handling function.
Merge pull request #115 from arjansingh/mocha-support

Mocha.js Engine Support
Merge pull request #118 from bowdev/em_refactor

Error Manager Refactoring
making workingDirectory null for sessionfactory unit tests, so that they dont exit midway.