RavenDB-1611. started working on voron transactional storage for RavenFS. Extracted interfaces.
implemented TransactionalStorage for ravenfs
working on ravenfs voron transactional storage
more work on voron transactional storage for ravenfs, added config tests
fixed GetConfigNames paging in esent transactional storage for ravenfs
added PageTests for voron transactional storage for ravenfs
implemented GetSignatures and AddSignature
implemented signature support for voron transactional storage for ravenfs
file methods for voron transactional storage for ravenfs
can configure transactional storage by settings
Merge branch 'New3' of https://github.com/ayende/ravendb into RavenDB-1611

Conflicts:
	Raven.Database/Server/RavenFS/Synchronization/DeleteWorkItem.cs
	Raven.Database/Server/RavenFS/Synchronization/MetadataUpdateWorkItem.cs
	Raven.Database/Server/RavenFS/Synchronization/RenameWorkItem.cs
after merge fixes
fixing tests
fixing GetFile in voron transactional storage for ravenfs
fixing issue RavenDB-1837: etag(in the form of If_none_Match header attribute) is not being sent upon save document
voron transactional storage for ravenfs fixes
file renames now work
issue  RavenDB-1575: implement CreateSampleData
Merge branch 'New3' of https://github.com/fitzchak/ravendb into New3
fixing GetFilesAfter