Use package for .env editing

The solution provided by this package is similar to what was previously implemented (see #1), but it's nicely packaged and made available in a Facade.

app/Console/Commands/Install.php

@@ -110,7 +110,7 @@ class Install extends Command
 
            foreach($settings as $keyname => $value)
            {
-              $this->callSilent('environment:modify', [
+              $this->call('environment:modify', [
                   'key' => $keyname,
                   'value' => $value
               ]);