(GH-510) Chocolatey should find tools in it's default install location

 - The default install location was updated, but some of the helpers were
   looking at this prior to checking the %ChocolateyInstall% variable to find a
   necessary tool. This fixes that.
 - This adds an attempt to update the session environment to grab the latest
   environment variables from the registry.
 - Updated some docs that were pointing to the old variable
 - Minor maintenance update to setup and processing bin-files to point to the
   correct directory.
(doc) do not give the impression that an actual virus scan is happening

 - Since the implementation we were hoping for is not going to be free from the
   vendors, we can't leave the debugging messages there that make it appear
   that we are checking for viruses when we are not.
(maint) formatting
(doc) fixed a missed word in shimgen licensing