Fixed typo in TLS log
DirectoryLayer: [Breaking Change!] renamed Fdb.PartitionTable helper into Fdb.Directory to be consisted with v2.0 API

- Fdb.Directory.OpenNamedPartitionAsync(....) will return a new db instance restricted to the partition's prefix, and with a DirectoryLayer whos root ('/') corresponds to the partition directory itself (this is equivalent of creating a chroot jail on a unix box.)
- The readOnly flag is set once the db has been chrooted, because the we need write access to create the partition if it did not exist.
- Fixed cancellation tokens not being flowed correctly
Renamed file to Fdb.Directory.cs, updated XML comments
Fixed sample project after DL changes