Update Javelin; improve package definitions

Summary:

• Update Javelin to HEAD -- this doesn't pick up anything in particular, but

lets us smoke test some stuff like {D1217}.

• Do a little more packaging since we've picked up a handful of 10-line

behaviors and such for various UI tweaks.

Test Plan:

• Generally, this should be very low-risk.
• Browed Maniphest, Differential, Diffusion and tried to hit all the JS

interactions.

• Looked over the Javelin changes we're pulling in to see if I forgot

anything. The only API change I caught was removal of "JX.defer()", but that was
already cleared in Phabricator in D803.

Reviewers: aran, btrahan, jungejason

Reviewed By: aran

CC: aran

Differential Revision: 1240