Usability for Cedar Test Bundle + Testing script tweaks.

Raise when running a Cedar test bundle w/o XCTest or SenTestingKit.

Having a separate scheme makes this easier to test because we can actually set it up
how a real user would. It is a little strange to have a test that always fails by design,
but considering how hard this is to unit test, this seems valuable

Many thanks to @wileykestner for the tip.

Feature specs are more resilient to textfield focus settings.

OS X has a system prefs setting to allow all UI controls to receive focus,
not just text fields. Setting that would break these feature specs.

Templated rakefile now raises an error when ios-sim is not present
Rakefile now always uses the latest iOS SDK. XCTest bundle is built
under 64-bit to avoid Xcode 5 test run failures.

Do not print path in cucumber rake step.
Wait for sheet to appear before continuing for applescript.
Suppress errors when failing to kill the simulator between test runs.