WIP: update protocol_validator

Pull in the protocol validator from the 0.10.0 release of the protocol.  This breaks our tests that use the validator.
WIP: Update the exported DAP '__version__'...

to 0.10.0.
Translate 'n' to 'b' on distarray export.
Add support for empty dict alias.
Add a blank line.
Add blank line.
Valid dist types now determined by validator.
Remove unused import.
Split round-trip tests into their own mixin.

Then, only run the round-trip tests on non-'n'-distributed LocalArrays.
Modify NOTE in docstring about when tests are applicable.
Merge pull request #296 from enthought/feature/update-protocol-impl

Update implementation of the distributed array protocol