server: expose injector from KillbillGuiceListener

Use the injector to access instances from server tests, similar to what we do
in other modules.

Signed-off-by: Pierre-Alexandre Meyer <pierre@ning.com>
Rework beatrix and server tests to use base class GuicyKillbillTestSuiteWithEmbeddedDB
Merge branch 'master' of github.com:killbill/killbill
Merge branch 'master' into new-paymentpluginapi

Conflicts:
	server/src/test/java/com/ning/billing/jaxrs/TestJaxrsBase.java
Merge branch 'new-paymentpluginapi' of github.com:killbill/killbill into new-paymentpluginapi