Remove unneeded assembly references from DDEX project

This pr will:
- Remove unneeded assembly references from DDEX projects.
- Divide DDEX projects from Vs2010+Vs2013 into Vs2010+**Vs2012**+Vs2013. Vs2013's one won't work on **Vs2012**.
- Add vssdk11_tools in order to build **Vs2012** DDEX project.