charm-tools is not python3 compatible

[Curtis Hovey]

The tools are not always ptyhon3 compatible. trusty will be the first lts that does not ship python2 by default. Authors can install python 2 to use these tools of course.

$ python3 /usr/bin/pocketlint -q `find . -name '*.py'`
./charmtools/proof.py
     171: Could not compile; invalid syntax: except Exception, error:
./charmtools/subscribers.py
     178: Could not compile; invalid syntax: print msg
./charmtools/review_queue.py
      77: Could not compile; invalid syntax: print "Connecting to launchpad..."
./charmtools/promulgate.py
     161: Could not compile; invalid syntax: except (BadRequest, NotFound), e:
./charmtools/create.py
      74: Could not compile; invalid syntax: print "Found " + package + " package in apt cache, as a result " \
./charmtools/list.py
      29: Could not compile; invalid syntax: print "\n".join(charms.remote())
./charmtools/review.py
      81: undefined name 'raw_input'
./charmtools/search.py
      38: Could not compile; invalid syntax: print '\n'.join(matches)
./charmtools/mr.py
      19: 'errors' imported but unused
./charmtools/charms.py
       2: 'sys' imported but unused
./ez_setup.py
     122: Could not compile; invalid syntax: except pkg_resources.VersionConflict, e:
./setup.py
      12: 'find_packages' imported but unused
       6: 'sys' imported but unused