test with Python 3.4 on Travis

exclude redundant js tests on 3.3
Don't hang tests if notebook server fails to terminate.
Popen.wait(timeout) is new in Python 3.3
fix cursor keys in long lines wrapped in markdown
cleanup socket cleanup

- set linger on sockets (avoid hang on exit)
- actually close sockets, not just zmq streams (blame pyzmq, aka me)

seems to be necessary for js/notebook/shutdown test to avoid hanging on Python 3.4.
set linger on every socket I can find

help cleanup sockets on 3.4
wait until dead *before* cleaning up the temp dir
reorder travis so slowest groups start first
Merge pull request #5775 from minrk/race-cleanup

wait until dead before cleaning up the temp dir
Merge pull request #5759 from minrk/travis-3.4

test with Python 3.4 on Travis
run cells with `silent=True` in `%run nb.ipynb`

- more consistent with running scripts
- avoids a bunch of uncapturable `Out[n]: ` outputs
  when running a notebook.
Merge pull request #5788 from minrk/run-nb-silent

run cells with `silent=True` in `%run nb.ipynb`
Merge pull request #5768 from ivanov/cm-uuddlrlrba

fix cursor keys in long lines wrapped in markdown