Added the endpoint property and appropriate accessors to the BufferedAdd plugin and added a call to the get accessor to be passed in to the update() call.

Conflicts:
	tests/Solarium/Tests/Plugin/BufferedAdd/BufferedAddTest.php

Event AddDocument for BufferedAdd plugin

Implemented an event which is fired on each document added to the BufferAdd plugin so you can provide some more status feedback while importing.

liberalised version of Symfony Event Dispatcher