* Update hash
* Add validateCapabilities and parseCapabilities
* Added merge capabilities
* Moved capabilities into it's own file
* Added capabilities as a possible required param
* Can pass desiredCapabilities or capabilities into createSession
* Remove 'required' desiredCapabilities
* desiredCapabilities isn't required any more because we can provide capabilities as well
* Will need to update validation logic in 'driver.createSession' to do the validation there instead
* Code cleanup
* Skip presence constraint in parseCapabilities
* We don't need to check that items are present until after we've formed the matched capabilities
* Added validation function to routes
* Function 'validate' takes params as an arg and then returns a message if the validation fails
* Uses this to validate that either "capabilities" or "desiredCapabilities" was provided
* Renamed capabilities to caps
* Move caps required validator from process to parse
* Removed InvalidParametersError
* Update BadParametersError so that if a message is added as the 3rd argument it shows a different error message
* Made validation re-usable
Dan Graham