Add support for beautifiers ignoring CLI return code

Rubocop always returns an error code (1) instead of a good code (0) so
the beautifier has now been configured to ignore the return code / exit
status for only Rubocop beautifier. Other beautifiers will properly
return error when an bad return code is received.

src/beautifiers/beautifier.coffee

@@ -128,7 +128,7 @@ module.exports = class Beautifier
     ###
     Run command-line interface command
     ###
-    run: (executable, args) ->
+    run: (executable, args, {ignoreReturnCode} = {}) ->
         # Resolve executable
         Promise.resolve(executable)
         .then((exe) =>
@@ -156,12 +156,12 @@ module.exports = class Beautifier
                         cmd.stdout.on('data', (data) -> stdout += data )
                         cmd.stderr.on('data', (data) -> stderr += data )
                         # when the spawn child process exits, check if there were any errors and close the writeable stream
-                        cmd.on('exit', (code) ->
-                            # console.log('spawn done', code, stderr, stdout)
+                        cmd.on('exit', (returnCode) ->
+                            console.log('spawn done', returnCode, stderr, stdout)
                             # If return code is not 0 then error occured
-                            # if code isnt 0
-                            #     reject(stderr)
-                            # else
+                            if not ignoreReturnCode and returnCode isnt 0
+                                reject(stderr)
+                            else
                                 resolve(stdout)
                         )
                         cmd.on('error', (err) ->

src/beautifiers/rubocop.coffee

@@ -16,7 +16,7 @@ module.exports = class Rubocop extends Beautifier
         @run("rubocop", [
                 "--auto-correct"
                 tempFile = @tempFile("temp", text)
-            ])
+            ], {ignoreReturnCode: true})
             .then(=>
                 # console.log('rubocop', arguments, tempFile)
                 @readFile(tempFile)