Add knitr and rmarkdown packages in AppVeyor tests

Author: HyukjinKwon

appveyor.yml

@@ -38,12 +38,8 @@ install:
   # Install maven and dependencies
   - ps: .\dev\appveyor-install-dependencies.ps1
   # Required package for R unit tests
-  - cmd: R -e "install.packages('testthat', repos='http://cran.us.r-project.org')"
-  - cmd: R -e "packageVersion('testthat')"
-  - cmd: R -e "install.packages('e1071', repos='http://cran.us.r-project.org')"
-  - cmd: R -e "packageVersion('e1071')"
-  - cmd: R -e "install.packages('survival', repos='http://cran.us.r-project.org')"
-  - cmd: R -e "packageVersion('survival')"
+  - cmd: R -e "install.packages(c('knitr', 'rmarkdown', 'testthat', 'e1071', 'survival'), repos='http://cran.us.r-project.org')"
+  - cmd: R -e "packageVersion('knitr'); packageVersion('rmarkdown'); packageVersion('testthat'); packageVersion('e1071'); packageVersion('survival')"
 
 build_script:
   - cmd: mvn -DskipTests -Psparkr -Phive -Phive-thriftserver package