Making changes to the environment variable DevEnvDir

Making changes to the environment variable "$(DevEnvDir)" since this is not available outside of VisualStudio. But accoding to Daniel Casselino(http://blogs.clariusconsulting.net/kzu/devenvdir-considered-harmful/) "$(VS120COMNTOOLS)..\IDE" is available outside of VisualStudio, this will be usefull if we have to integrate this in CI