fix(bootstrap-prettify): share $animate and $$postDigestQueue with demo apps

Although demo apps run in an isolated environment, we need to be able to tell them to disable
animations when we are running end-to-end tests.  By sharing the same instance of $animate
between the two environments we can disable animation across the board.

The $animate service uses the $$postDigestQueue to run animations.  The outer $animate
service uses the outer $$postDigestQueue and to queue up these animations.  This means that
when we run a digest inside the embedded scope, the animations are never performed - they
just sit in the outer scope's queue and are only run when a digest is run on the outer scope.
By sharing this queue across the two scopes the animations are performed correctly.
refactor($animate): speed up animationsDisabled check
fix($animate): don't force animations to be enabled

The way that enabling of animations was set up, made it impossible to inject a
module into the bootstrap to disable animations for things like end 2 end tests.
Now animations are temporarily blocked by setting the animation state to RUNNING
during bootstrap, which allows the developer to permanently disable at any point
by calling $animate.enabled(false).
fix(ngScenario): correctly disable animations for end 2 end tests
fix(ngClassSpec): clear animation enable fn from postDigestQueue
fix(animateSpec): run digest to enable animations before tests