swift-mock: better name for Swift mock

We will be moving the client-side code out of this file and call that
code a Swift simulator.
swift-simulator: move code out of swift-mock (fixes #59)

This makes it possible to debug the code in the simulator: the code is
loaded using a script element during testing and this makes it
possible to set breakpoints like normal when the browser is paused
with a call to browser.pause() in a test.
swift-mock: move JSON wrapping out of swift-simulator
Merge pull request #70 from mgeisler/swift-mock

Push swift simulator code into client-side script