Three fixes: getting the BridgeDb databases to load

I discovered today that on Jenkins the unified identifiers are not created. These patches fix:

* download the metabolites ID mapping db too
* fixed the filter so that loading really works

PS. while Alex gave me commit rights, that cannot push commits directly into the repos:

    $ git push origin master 
    ERROR: Permission to wikipathways/wp2lod.git denied to egonw.
    fatal: Could not read from remote repository.
    
    Please make sure you have the correct access rights
    and the repository exists.