karma: don't include app/js/test files

Karma accidentally included the JavaScript files in app/js/test/.
These files are not intended to be included when the unit tests run:
including swift-simulator.js is harmless, but the upcoming mock-env.js
cannnot be included unconditionally.
grunt: add mock task (fixes #117)

This generates a mock.html which will load the Swift simulator and
configure a basic test environment. The simulator is loaded in the
same way Protractor loads it (this can probably be simplified now).

You will be working on an in-memory database which reflects the
changes you make until you reload the page. Navigating using the
in-page links is okay since that doesn't trigger a full page reload.
readme: explain how to start mock environment
mock: add large container with 1000+ objects