Remove obsolete environment variable in build

Author: AArnott

appveyor.yml

@@ -1,14 +1,9 @@
-version: 1.0.{build}
+version: '{build}'
 skip_tags: true
 os: Visual Studio 2015
 configuration: Release
 environment:
   VisualStudioVersion: 14.0
-  DeployExtension: False
-  NuGetApiKey:
-    secure: Ql19CstT9GvFNeSIAjXvgHXZg+/pNaYJ2jVkzde4LT2vwSyjiQgQ+M332wVYtu+r
-cache:
- - '%USERPROFILE%\.nuget\packages -> **\project.json'
 install:
 - ps: >-
     iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/install-nuget-3-3-0.ps1'))