Supporting Google App Engine

I wanted my RESTler-powered API to migrate to Google App Engine, but when running my code on the development server, I always got Error 404 from RESTler.

Then I noticed that the request url in GAE always starts with a slash. So it has the following format: /v1/users...

Then I debugged the code and found that ```Restler::getPath()``` method has a minor bug. If the requests starts with a slash then the ```path``` and even ```version``` variables don't initialize well.

P.S.: Anyway, RESTler does not run on Google App Engine, yet. There are some problems with it, but I'll try to make a new pull request soon.