WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Quick and dirty implementation of WicketAtmosphereTester

(cherry picked from commit 2ab1d798e3348ba7037ab461e1be6df55cd68457)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Atmosphere tester - write to the http response (doesn't work)

(cherry picked from commit 0582a24373b2bcd981f398c39f8cfea85cd08e06)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Fix the atmosphere behavior listener interface's type

(cherry picked from commit d0751c2b1de861222f4b53fdcc76dc7719c0ff38)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Rename WicketAtmosphereTester to AtmosphereTester

Start the page after configuring AtmosphereTester/TesterEventBus so the method collector is called for all components in the page
Expose TesterBroadcasterFactory as BroadcasterFactory#getDefault()

(cherry picked from commit e841383c045f62d5feb87413f1aa6f694df8dcb7)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Fix the callback url to the AtmosphereBehavior. It should be an Ajax one to prevent incrementing of the page id/renderCount

(cherry picked from commit 0b770b05e0f7b86cbe647a155dfe1a82f1bccc3a)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Pretend being a websocket request when using AtmosphereTester

(cherry picked from commit 2239d1e17f2a23011709815ba6eedbaf5baf8f5e)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Upgrade Atmosphere to 2.1.8

(cherry picked from commit 2524554a3b26b63c2f42c895505d3a7638d3edd6)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Make it possible to write to the underlying http response

(cherry picked from commit beeb0001ac71001c7fddaf519109e73a28649457)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Pretend it is WebSocket connection

(cherry picked from commit 5513936eb4decd56a4ab5be07f499f47ace255ca)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Remove custom executors - they are no needed because of TesterBroadcaster#executeBlockingWrite(AtmosphereResource, Entry)

(cherry picked from commit 2a52b360bf964a162cf8e76d94ad3d42ae17fd88)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Add ASL2 headers

(cherry picked from commit 4a38ae18cc76534f7fa7ace4a3f19cd44c7e41c0)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Reuse the already installed EventBus in MyApp#init. Just set TesterBroadcaster for testing purposes.

Add APIs to make it possible to assert on the suspended (by Atmosphere) http response

(cherry picked from commit 77d0a46ef018a1bb35282fbb374d9de56ac51c39)
WICKET-5452 Make Wicket-Atmosphere testable - AtmosphereTester

Fix a typo in javadoc. Use Hamcrest matchers

(cherry picked from commit 66bff0b1351f6559c6a102250bc5a56bf6cd9069)