Enable email notifications from Travis CI

http://docs.travis-ci.com/user/notifications/
> By default, email notifications will be sent to the committer and the commit author, if they are members of the repository (that is, they have push or admin permissions for public repositories, or if they have pull, push or admin permissions for private repositories).
>
> And it will by default send emails when, on the given branch:
>
> * a build was just broken or still is broken
> * a previously broken build was just fixed
Include some jemalloc stats in the -m measurements.
adding 2 new default arguments when running make check-wpt so that it does not fail saying KeyError: 'debug_args' or KeyError: 'interactive'
Update run.py

None and False are better values here (thanks to @jgraham).
Store proxy handlers in a static array rather than a hashtable per window.
Remove references to WindowProxy as an interface.
Add a test for interfaces exposed on the window object.
Stop exposing XMLHttpRequestEventTarget on the window object.
Merge pull request #2808 from schaars/make_check-wpt

adding 2 default arguments to src/test/wpt/run.py; r=jgraham,Ms2ger
Handle exceptions from JS_ParseJSON in XMLHttpRequest.response.
Merge pull request #2810 from Ms2ger/proxy-handlers

Store proxy handlers in a static array rather than a hashtable per window.
Merge pull request #2813 from Ms2ger/WindowProxy

Remove references to WindowProxy as an interface.
Merge pull request #2815 from Ms2ger/test_interfaces

Add test_interfaces.html.
Merge pull request #2817 from Ms2ger/xhr-response-json

Handle exceptions from JS_ParseJSON in XMLHttpRequest.response.
Remove empty objects from Bindings.conf.

This also comments out an unused mixin interface, and adds
NoInterfaceObject to one that missed it.
Pass a JSContext and a reflector to RegisterBindings::Register.

This makes the generated code less dependent on the fact that all global
objects are Windows.
Move the call to RegisterBindings::Register into WindowBinding::Wrap.
Update the rust-mozjs submodule pointer.
Fix DOMImplementation should be linked to the Document

This fixes issues 2230.
Merge pull request #2816 from Ms2ger/bindings.conf

Cleanup Bindings.conf.