Deprecated the URL alteration in visit()

This was introduced to strip the base url from the url when using the
HttpKernel client in early versions of the driver. However, this was only
half-working as it was impacting the current url later. A proper way to
support the base url has been introduced for the HttpKernel client, so the
old one can be deprecated.
Changed the default value of removeScriptFromUrl to false

This is a much more sensible default, as highlighted by the fact that it
was needed for the testsuite. This is now applied even without a base url.
Merge pull request #69 from stof/deprecate_url_alteration

Deprecated the URL alteration in visit()
Updated the driver for the Mink 2.0 API
Removed the BC layers for Symfony 2.2 and older
Removed the deprecated url altering