This reverts commit be93b6ea28.
Unfortunately, the newer jquery comes with a huge performance
regression affecting the hotkeys code, which has the effect of making
typing super slow.
Fixes: #1449.
The node packages 'jQuery' and 'jquery' are different--'jQuery' is the
legacy support package that is needed for Zulip so the require statements
in the tests were updated.
Travis uses node 4.0 by default and we are using 0.10, so the command to
install the correct version had to be added to the .travis.yml file.
