Changed "except" statement to Python3 form

Changed "except Exception, e" to "except Exception".
In Python 3, the grammar for except statements is 
except_clause: 'except' [test ['as' NAME]]
Fix link following in poll_rss command.
Added Vitaliy Kharin to AUTHORS.
Added required settings for search for latest Mezzanine version. Closes #12.
Nice error message formatting
Added support for links being optional (ala Reddit/HN 'self' posts).
Version bump to 0.2
Include footer_scripts.html
Move tumblr hack in poll_rss command to subclassed command.
Clean up link admin styles
Better search fields for link admin
Updated setup.py from Mezzanine.
Version bump to 0.2.1