Upgrade to Underscore 1.4.4.
Improve test driver performance.

Upgrading Underscore to 1.4.4 fixes a bug where _.throttle would sometimes take
double its timeout to deliver calls. So with this bugfix, our test suite
performs worse because reactivity happens more often. Reduce the throttling to
one update of the big table per second instead of twice a second. (Also, there's
no need to defer and call flush; the changed call does that!)
Upgrade Connect to 2.x.

Set $NODE_ENV appropriately (to 'development' in 'meteor run' and 'production'
otherwise) so that connect doesn't send stack traces over the network in
production.
Bump dev bundle version for connect and underscore upgrades.

(0.3.4 was used on the linker branch.)
Update HISTORY for upgrades.
Merge branch 'connect-underscore-upgrades' into devel
Update shrinkwrap file because mongodb module got re-pushed.

mongodb 1.3.6 was originally published depending on bson 0.1.8 and was
re-published depending on 0.1.9 (oops).