Made undefined variable connection expression error message more specific.
Removed 'parent' arg from _needs_pseudo_comp function signature because it's not used.
Merge branch 'dev' of https://github.com/OpenMDAO/OpenMDAO-Framework into mpi
Removed test_metadata_link. Modified error message for clarity when scope is top level assembly. Added tests for error messages from different scopes.
Merge pull request #1857 from crobinsonut/mpi

Made connection expression error message for undefined variables more specific