[SPARK-21805][SPARKR] Disable R vignettes code on Windows

## What changes were proposed in this pull request?

Code in vignettes requires winutils on windows to run, when publishing to CRAN or building from source, winutils might not be available, so it's better to disable code run (so resulting vigenttes will not have output from code, but text is still there and code is still there)

fix * checking re-building of vignette outputs ... WARNING
and
> %LOCALAPPDATA% not found. Please define the environment variable or restart and enter an installation path in localDir.

## How was this patch tested?

jenkins, appveyor, r-hub

before: https://artifacts.r-hub.io/SparkR_2.2.0.tar.gz-49cecef3bb09db1db130db31604e0293/SparkR.Rcheck/00check.log
after: https://artifacts.r-hub.io/SparkR_2.2.0.tar.gz-86a066c7576f46794930ad114e5cff7c/SparkR.Rcheck/00check.log

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes apache#19016 from felixcheung/rvigwind.

R/pkg/DESCRIPTION

@@ -2,7 +2,7 @@ Package: SparkR
 Type: Package
 Version: 2.1.2
 Title: R Frontend for Apache Spark
-Description: The SparkR package provides an R Frontend for Apache Spark.
+Description: Provides an R Frontend for Apache Spark.
 Authors@R: c(person("Shivaram", "Venkataraman", role = c("aut", "cre"),
                     email = "shivaram@cs.berkeley.edu"),
              person("Xiangrui", "Meng", role = "aut",

R/pkg/R/install.R

@@ -270,7 +270,11 @@ sparkCachePath <- function() {
   if (.Platform$OS.type == "windows") {
     winAppPath <- Sys.getenv("LOCALAPPDATA", unset = NA)
     if (is.na(winAppPath)) {
-      stop(paste("%LOCALAPPDATA% not found.",
+      message("%LOCALAPPDATA% not found. Falling back to %USERPROFILE%.")
+      winAppPath <- Sys.getenv("USERPROFILE", unset = NA)
+    }
+    if (is.na(winAppPath)) {
+      stop(paste("%LOCALAPPDATA% and %USERPROFILE% not found.",
                    "Please define the environment variable",
                    "or restart and enter an installation path in localDir."))
     } else {

R/pkg/vignettes/sparkr-vignettes.Rmd

@@ -27,6 +27,17 @@ vignette: >
  limitations under the License.
 -->
 
+```{r setup, include=FALSE}
+library(knitr)
+opts_hooks$set(eval = function(options) {
+  # override eval to FALSE only on windows
+  if (.Platform$OS.type == "windows") {
+    options$eval = FALSE
+  }
+  options
+})
+```
+
 ## Overview
 
 SparkR is an R package that provides a light-weight frontend to use Apache Spark from R. With Spark `r packageVersion("SparkR")`, SparkR provides a distributed data frame implementation that supports data processing operations like selection, filtering, aggregation etc. and distributed machine learning using [MLlib](http://spark.apache.org/mllib/).