R-release appveyor test

appveyor.yml

@@ -5,10 +5,22 @@ environment:
    - PYTHON: "C:\\Python27-x64"
      PYTHON_VERSION: "2.7.x"
      PYTHON_ARCH: "64"
+     R_VERSION: "release"
 
    - PYTHON: "C:\\Python36-x64"
      PYTHON_VERSION: "3.6.x"
      PYTHON_ARCH: "64"
+     R_VERSION: "release"
+
+   - PYTHON: "C:\\Python27-x64"
+     PYTHON_VERSION: "2.7.x"
+     PYTHON_ARCH: "64"
+     R_VERSION: "devel"
+
+   - PYTHON: "C:\\Python36-x64"
+     PYTHON_VERSION: "3.6.x"
+     PYTHON_ARCH: "64"
+     R_VERSION: "devel"
 
 init:
   - "ECHO %PYTHON% %PYTHON_VERSION% %PYTHON_ARCH%"
@@ -25,3 +37,7 @@ install:
   - "%CMD_IN_ENV% pip install -e .[test]"
 test_script:
   - "%CMD_IN_ENV% pytest"
+
+# on_finish:
+# # uncomment to enable RDP to Appveyor
+#   - ps: $blockRdp = $true; iex ((new-object net.webclient).DownloadString('https://raw.githubusercontent.com/appveyor/ci/master/scripts/enable-rdp.ps1'))