Fix jshint warnings

`grunt jshint` completes successfully now.
Allow end-user configuration of baseUrl.

This makes it easier to use a local copy of TogetherJS, without requiring
a rebuild from sources.
Suppress 'Unknown configuration value' warning for 'lang'.
Allow cache-busting to be disabled.
Gracefully handle missing peers in old chat log history.
Fix youtube support.

We need to add the 'enablejsapi=1' parameter to the source URL in
order to get API events for embedded youtube iframes.  Also use the
appropriate `Player#getIframe()` API instead of the sketchy `a` field,
and play nicely in case somebody has already added a hook to
`window.onYouTubeIframeAPIReady`.
Update jquery from 1.8.3 to 1.11.1.

This fixes a bug with 'change' events on text input fields in recent
webkit versions (found with the test suite).
Update test suite; make all tests pass once more.

The doctest.js test suite had rotted a bit; made the appropriate changes
necessary to get it running again.

Removed two tests which had rotted and tested code which is unused.
Send form-init before form-focus; make form test case more reliable.

Eliminate some time-based wait() statements in the func_forms.js test
case to make it deterministic.  Also make ACE/CodeMirror tests more
reliable.
Hook up doctest.js to phantomjs and travis for CI testing.
Add hixie-76 websocket support; turn on additional phantomjs tests.

Add support for (old, obsolete) hixie-76 websockets, which not
coincidentally happen to be the version of the websocket standard
supported by phantomjs 1.x.

This allows us to turn on the functional tests in the doctestjs suite.
Merge pull request #1026 from cscott/test-suite

Cleanups and fixes; make test suite work once more.