Add DynamoAddinGenerator tool.

Consolidates logic for finding installed versions of Dynamo and Revit
and generating the appropriate addins.
Add tests.
Cleanup and add some comments.
Change install folder name.
Copy AddinGenerator during installer creation.

Remove addin batch file calls from installer.
Remove addin creation from installer.
Add DynamoAddinGenerator to installer.
Switch project to x64.

Without this switch, the environment special folders will not path
correctly to Program Files and Program Files (x86).
Bundle the 2015 addin utility in the installer.
Remove duplicate name in addin.
Remove addin contents variable.
Fix xml closing tag in addin.
Make DllForLoadFile unique to revit version.
Merge pull request #1768 from DynamoDS/DynamoAddinGenerator

Dynamo Addin Generator