(#149) Write out all environment variables
(#149) Write out all environment variables

- Using the list here:
  http://www.appveyor.com/docs/environment-variables

  Write out all the environment variables from the Build Worker for reference purposes, which can then be inspected and appropriate action taken.

sayedihashimi/ChocolateyGUI,chocolatey/ChocolateyGUI,gep13/ChocolateyGUI,alephnaughty/ChocolateyGUI,gep13/ChocolateyGUI,gep13/ChocolateyGUI,digital-carver/ChocolateyGUI,dlsteuer/ChocolateyGUI,RichiCoder1/ChocolateyGUI,chocolatey/ChocolateyGUI,gep13/ChocolateyGUI,chocolatey/ChocolateyGUI,wjk/ChocolateyGUI,paladique/ChocolateyGUI,chocolatey/ChocolateyGUI,paladique/ChocolateyGUI,M-Zuber/ChocolateyGUI,chocolatey/ChocolateyGUI,gep13/ChocolateyGUI