Signed connection ids.
- Added API to Protect/Unprotect data.
- Default implementation uses DPAPI.
- Updated tests.
- Fixed issues in .NET client where connection ids were not encoded.
- Added ASP.NET specific ProtectedData that uses the MachineKey

#1305
Made scope in DefaultProtectedData configurable.
- Default is per User.
Made MachineKeyProtectedData40 a static class.

#1305