Add scalastyle linter (#766)

* Add support for scalastyle

* Add scalastyle docs

* scalastyle support for column numbers

* off by one column

* Add tests for scalastyle command and handler

* update readme for scalastyle

* allow full scalastyle options instead of just config file

* fix indentation

* allow scalastyle config file in parent directories by a couple names.

* check for missing match args with empty

* remove echo

* use a for loop

doc/ale.txt

@@ -93,6 +93,8 @@ CONTENTS                                                         *ale-contents*
       rustc...............................|ale-rust-rustc|
     sass..................................|ale-sass-options|
       stylelint...........................|ale-sass-stylelint|
+    scala.................................|ale-scala-options|
+      scalastyle..........................|ale-scala-scalastyle|
     scss..................................|ale-scss-options|
       stylelint...........................|ale-scss-stylelint|
     sh....................................|ale-sh-options|
@@ -206,7 +208,7 @@ The following languages and tools are supported.
 * Ruby: 'reek', 'rubocop'
 * SASS: 'sasslint', 'stylelint'
 * SCSS: 'sasslint', 'scsslint', 'stylelint'
-* Scala: 'scalac'
+* Scala: 'scalac', 'scalastyle'
 * Slim: 'slim-lint'
 * SML: 'smlnj'
 * Stylus: 'stylelint'