Fix MAGN-2213 Crash while placing custom node downloaded from Package Manager
Merge pull request #1286 from Benglin/MAGN-2213

Merging this in due to its urgent nature (testing impact).
Test cleanup

- Fixed few NUNIT failures due to missing math.dll, replaced the call to
use DSCoreNodes.dll which implements Math class
- The validation for few node migration tests have been updated.
Merge pull request #1287 from sharadkjaiswal/DataMarshaling

Test cleanup
Fix gitignore and re-track ASM folder.
Update ASM ignore.