[SPARK-16425][R] describe() should not fail with non-numeric columns

## What changes were proposed in this pull request?

This PR prevents ERRORs when `summary(df)` is called for `SparkDataFrame` with not-numeric columns. This failure happens only in `SparkR`.

**Before**
```r
> df <- createDataFrame(faithful)
> df <- withColumn(df, "boolean", df$waiting==79)
> summary(df)
16/07/07 14:15:16 ERROR RBackendHandler: describe on 34 failed
Error in invokeJava(isStatic = FALSE, objId$id, methodName, ...) :
  org.apache.spark.sql.AnalysisException: cannot resolve 'avg(`boolean`)' due to data type mismatch: function average requires numeric types, not BooleanType;
```

**After**
```r
> df <- createDataFrame(faithful)
> df <- withColumn(df, "boolean", df$waiting==79)
> summary(df)
SparkDataFrame[summary:string, eruptions:string, waiting:string]
```

## How was this patch tested?

Pass the Jenkins with a updated testcase.

Author: Dongjoon Hyun <[email protected]>

Closes apache#14096 from dongjoon-hyun/SPARK-16425.

R/pkg/R/DataFrame.R

@@ -2622,8 +2622,7 @@ setMethod("describe",
 setMethod("describe",
           signature(x = "SparkDataFrame"),
           function(x) {
-            colList <- as.list(c(columns(x)))
-            sdf <- callJMethod(x@sdf, "describe", colList)
+            sdf <- callJMethod(x@sdf, "describe", list())
             dataFrame(sdf)
           })
 

R/pkg/inst/tests/testthat/test_sparkSQL.R

@@ -1824,13 +1824,17 @@ test_that("describe() and summarize() on a DataFrame", {
   expect_equal(collect(stats)[2, "age"], "24.5")
   expect_equal(collect(stats)[3, "age"], "7.7781745930520225")
   stats <- describe(df)
-  expect_equal(collect(stats)[4, "name"], "Andy")
+  expect_equal(collect(stats)[4, "name"], NULL)
   expect_equal(collect(stats)[5, "age"], "30")
 
   stats2 <- summary(df)
-  expect_equal(collect(stats2)[4, "name"], "Andy")
+  expect_equal(collect(stats2)[4, "name"], NULL)
   expect_equal(collect(stats2)[5, "age"], "30")
 
+  # SPARK-16425: SparkR summary() fails on column of type logical
+  df <- withColumn(df, "boolean", df$age == 30)
+  summary(df)
+
   # Test base::summary is working
   expect_equal(length(summary(attenu, digits = 4)), 35)
 })