make RandomStream "seekable"
make RandomStream "seekable"

in the same way NullStream was made seekable

Change-Id: I3dce30b8b4c883e53e24e973f5da66860a9970ef
Reviewed-on: https://gerrit.dechocorp.com/6318
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@mozy.com>

adfin/mordor,mtanski/mordor,mozy/mordor,cgaebel/mordor,ccutrer/mordor,mtanski/mordor,mozy/mordor,adfin/mordor,mtanski/mordor,mozy/mordor,ccutrer/mordor,adfin/mordor,cgaebel/mordor,ccutrer/mordor