RavenDB-2421 Multi-tenant scaling and concurrent request limits

Conflicts:
	Raven.Abstractions/Data/Constants.cs
	Raven.Database/Config/InMemoryRavenConfiguration.cs
	Raven.Database/Config/StronglyTypedRavenSettings.cs
	Raven.Database/Server/HttpServer.cs
Fix merge
Merge branch 'master' of github.com:ayende/ravendb
Merge branch 'master' of github.com:ayende/ravendb

Conflicts:
	Raven.Database/Config/InMemoryRavenConfiguration.cs
	Raven.Database/Config/StronglyTypedRavenSettings.cs