Merge pull request #14 from ajbeamon/master

Remove various checks for null paths.
Remove checks for empty string paths to be compatible with other directory layer implementations
Revert previous change to allow empty strings in path and rewrite it to still check for null path elements.

This reverts commit 162854fb021f369705b27e3fabc2c8721231ae7f.
Merge pull request #15 from ajbeamon/master

Remove checks for empty string paths
Renamed begin/end to beginInclusive/endExclusive to match naming conventions, added XML comments
Merge branch 'master' of https://github.com/ajbeamon/foundationdb-dotnet-client into binding-tester