bug #721 Fix: Remove trailing whitespace if value is empty (OskarStark)

This PR was squashed before being merged into the 1.9-dev branch.

Discussion
----------

Fix: Remove trailing whitespace if value is empty

This is the case if someone wants to add a blank line.

```diff
# IMPORTANT: Comment
-#
+#
# FOO_BAR=baz
```

Commits
-------

9eaece7 Fix: Remove trailing whitespace if value is empty

Author: fabpot

src/Configurator/EnvConfigurator.php

@@ -51,7 +51,11 @@ private function configureEnvDist(Recipe $recipe, $vars, bool $update)
             foreach ($vars as $key => $value) {
                 $value = $this->evaluateValue($value);
                 if ('#' === $key[0] && is_numeric(substr($key, 1))) {
-                    $data .= '# '.$value."\n";
+                    if ('' === $value) {
+                        $data .= "#\n";
+                    } else {
+                        $data .= '# '.$value."\n";
+                    }
 
                     continue;
                 }