1. Fix: MAGN-261 Paste input/output node is crashing Dynamo
2. Added three new test cases to verify the fix
3. Added "InternalsVisibleTo" attribute to "DynamoCore" so its internals are visible to "DynamoCoreTests.dll"
Merge pull request #548 from Benglin/MAGN261

Fix for showstopper defect MAGN-261