Fix MAGN-5050 Import instance is updated in Dynamo, creates multiple instances in Revit
Add a test case
Merge branch 'magn-5050' of https://github.com/Randy-Ma/Dynamo into Randy-Ma-magn-5050
Merge pull request #3103 from DynamoDS/Randy-Ma-magn-5050

Randy ma magn 5050
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into Revit2015

Conflicts:
	test/Libraries/Revit/RevitTestServices/SystemTestBase.cs
Merge branch 'Revit2015' of https://github.com/DynamoDS/Dynamo into RC0.7.4_Revit2015