select Voron as default store engine if nothing is configured
Merge branch 'New3' of github.com:ayende/ravendb into New3
Merge branch 'New3' of github.com:ayende/ravendb into New3
fix for test RavenDB_551::ManyConcurrentDeleteForSameId()
Merge branch 'New3' of github.com:ayende/ravendb into New3

Conflicts:
	Raven.Database/Config/InMemoryRavenConfiguration.cs