RavenDB-1188 Improve indexing stats
Force random waits for concurrency conflicts in patching.
This will reduce the chance that competing threads will keep throwing each other into errors.
Merge branch '2.5' of github.com:DanielDar/ravendb into 2.5
Avoid error if retries is very small
Merge branch 'temp' of github.com:ayende/ravendb into 2.5

Conflicts:
	Raven.Database/DocumentDatabase.cs