Attempt to fix rscript for Linux

.travis.yml

@@ -107,6 +107,7 @@ before_install:
   # R
   - brew tap homebrew/science
   - brew install r
+  - rscript --version
   # PHP
   - brew tap homebrew/homebrew-php
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then

src/beautifiers/formatR/index.coffee

@@ -12,7 +12,7 @@ module.exports = class R extends Beautifier
   executables: [
     {
       name: "Rscript"
-      cmd: "Rscript"
+      cmd: "rscript"
       homepage: "https://github.com/yihui/formatR"
       installation: "https://github.com/yihui/formatR"
       version: {
@@ -32,9 +32,9 @@ module.exports = class R extends Beautifier
   }
 
   beautify: (text, language, options) ->
-    rScript = @exe("Rscript")
+    rscript = @exe("rscript")
     r_beautifier = path.resolve(__dirname, "formatR.r")
-    rScript.run([
+    rscript.run([
       r_beautifier,
       options.indent_size,
       @tempFile("input", text),