Edited Issue: Designer tests don't run on a machine that has both VS2012 and VS2013 installed [1505]

There seem to be multiple issues related to the VS host that effectively prevent the tests from running on a machine that has both versions of VS installed, regardless of whether you are doing the VS2012 or the VS2013 build.

In addition to that the wixproj for VSIDETestHost needs to be fixed to use WixExtDir variable for the path to the Wix Tools instead of reading the hardcoded registry setting.