Added some missing SauceLabs capabilities

Closes #126

src/Behat/MinkExtension/ServiceContainer/Driver/SauceLabsFactory.php

@@ -73,11 +73,22 @@ class SauceLabsFactory extends Selenium2Factory
                 ->scalarNode('platform')->defaultValue('Linux')->end()
                 ->scalarNode('selenium-version')->defaultValue('2.31.0')->end()
                 ->scalarNode('max-duration')->defaultValue('300')->end()
+                ->scalarNode('command-timeout')->end()
+                ->scalarNode('idle-timeout')->end()
                 ->scalarNode('build')->info('will be set automatically based on the TRAVIS_JOB_NUMBER environment variable if available')->end()
                 ->arrayNode('custom-data')
                     ->useAttributeAsKey('')
                     ->prototype('variable')->end()
                 ->end()
+                ->scalarNode('screen-resolution')->end()
+                ->scalarNode('tunnel-identifier')->end()
+                ->arrayNode('prerun')
+                    ->children()
+                        ->scalarNode('executable')->isRequired()->end()
+                        ->arrayNode('args')->prototype('scalar')->end()->end()
+                        ->booleanNode('background')->defaultFalse()->end()
+                    ->end()
+                ->end()
                 ->booleanNode('record-video')->end()
                 ->booleanNode('record-screenshots')->end()
                 ->booleanNode('capture-html')->end()