Add support for URLs as package_name in providers/pip current_installed_version comparison

In case we use an URL (as package_name) for pip we have to filter out 
the real package_name from such an URL (means: We remove all unneeded
parts).

In the next step we can use the extracted package_name as usual too look up and compare with current installed packages. 

Without such a change, the current_installed_version always returns NIL.



Signed-off-by: Martin Wilhelm <martin@system4.org>