[emacs mode] Require url-http

Issue #4
Simplify origin storing, make condense.js notice globals with external type
Add by-origin purging functionality
Overhaul tern.js internals

In preparation for a more eager loading/analysis model.
Add support for null queries

Which just push new versions of files to the server.
Fix bug in variable purging
Fix =/== typo
Fix bug in synchronous loading of files
[emacs mode] Fix bug that triggered end-of-buffer exception
[emacs mode] Add a tern-get-type (C-c C-c) binding
Make sure instances of constructors get a sane name
Also purge types from cx.props
Get rid of negative (dontSort, etc) options in completions service