framenet.py: doctest fixes for Python 3.x compatibility

see #479
framenet.py: set syntax
framenet.py: move sorting of relations into {frame,fe}_relations() for consistency; doctest fixes
Merge pull request #491 from nschneid/patch-8

framenet.py: doctest fixes for Python 3.x compatibility
fixed teardown_module

nose doesn't always pass 'module' argument to teardown_module functions
fixed metrics.doctest for Python 2.6