fix of Page::Search bug (that was rolled back for unknown reason)
fixed a problem with Tree::MultiAdd() --> adding multiple times the same key/val pair
Merge commit '079cba3e8df6530ff1d923eff8ca0dbb6d738f55' into 2.5-voron

Conflicts:
	Raven.Voron/Voron.Tests/MultiValueTree.cs
	Raven.Voron/Voron/Trees/Page.cs
	Raven.Voron/Voron/Trees/Tree.cs
changed functionality of SnapshotReader::Read() and SnapshotReader::ReadVersion() so they take into account WriteBatch changes and changed storage actions accordingly
Merge branch '2.5-voron' of https://github.com/ppekrol/ravendb into 2.5-voron