remove unused modules from browserification.
Moved pretty-date.js into lib/browser.
smaller help and filter buttons.
get userId from login server and expose it; we'll need it for #8.
Added lib/browser/session.js

All session-relevant custom meta tags are now prefixed with 'session-',
and get put into the session module's exports.

Also added test/browser/log-errors.js, which outputs any error events
to the console, making debugging easier with phantomjs.

One odd wrinkle is that bundle.js now needs to be loaded in the test
suite, yet it was throwing an error because qunit's definition of
'module' made the make API client think it was being loaded in node, so
qunit *must* be loaded after bundle.js.