Appveyor config for R package. See yml for details

appveyor.yml

@@ -1,13 +1,12 @@
 # DO NOT CHANGE the "init" and "install" sections below
 
-environment:
-  PKG_DIR: R
-
+# https://github.com/krlmlr/r-appveyor/issues/34#issuecomment-302016795
 before_build:
-  - cp ..\travis-tool.sh .\travis-tool.sh
-  - cp travis-tool.sh.cmd %PKG_DIR%\travis-tool.sh.cmd
-  - cd %PKG_DIR%
-  - bash -c "echo '^travis-tool\.sh\.cmd$' >> .Rbuildignore"
+  ps: |
+        cp ..\travis-tool.sh R\travis-tool.sh
+        cp travis-tool.sh.cmd R\travis-tool.sh.cmd
+        cd R
+        bash -c "echo '^travis-tool\.sh\.cmd$' >> .Rbuildignore"
 
 # Download script file from GitHub
 init: