Cleaning up units library

- Fixes defect http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-2465
- Fixed an issue in FFI, to pass the attributes on Enum as well to DS
Engine, so that Enums can be hidden.
Fix the test case for units.

- Removed Assert.Inconclusive
- Updated the validation code.
Merge pull request #1366 from sharadkjaiswal/070Countdown

Cleaning up units library