Simplify $$ methods in $FirebaseArray
src/FirebaseArray.js
 - _notify renamed to $$notify
 - _process renamed to $$process
 - $$process no longer called internally by $$added/$$updated/$$moved/$$removed
 - $$added now returns a record
 - $$updated now returns a boolean indicating whether anything changed
 - $$moved now returns a boolean indicating whether record should be moved
 - $$removed now returns a boolean indicating whether record should be removed
src/firebase.js: SyncArray to support new $$process usage
 - $$process now called after $$added, $$updated, $$removed, and $$moved (instead of coupled to those methods)
 - $$updated, $$moved, and $$removed only called if rec exists in the array
test/jasmineMatchers.js: added toHaveCallCount(), toBeEmpty(), and toHaveLength()
Replace references to .name() with .key()
Grammar
Merge pull request #458 from firebase/kato-extendArrayFactory

Simplify $extendFactory for $FirebaseArray