getPathToLibrary is now a public plugin method

getpathtolibrary is needed in the sergeant to verify integrity (md5sum)
of dependency

Signed-off-by: Luca Clementi <luca.clementi@gmail.com>
Fix in getPathToLibrary to avoid infinite recursion with python file

When getPathToLibrary was invoked with a python dependecy it created
an in loop invoking itself.
Verify integrity now it uses dinamyc path

When running an integrity verification of a swirl it now
finds where the new dependency are dinamically instead
of using the path from the swirl

Signed-off-by: Luca Clementi <luca.clementi@gmail.com>