FIX: meta tags
Fix the fact that the getMetadataFields now returns a dict with
FileMetadataFields and DirectoryMetadataFields 
Catch the case someone puts a meta tag that's at file level as there is
no support for getCompatibleMetadata at file level yet
Merge pull request #1362 from sposs/FCimprovements

FIX: "meta tags" failing the "where" clause