Feature/segment caching

I'd like to get some feedback on this before merging into master.

**Usage:**
Within any of your application modules ```onBootstrap()``` methods, you can do:

```php
$serviceLocator = $event->getApplication()->getServiceManager();
$parserManager = $serviceLocator->get('Dash\Router\Http\Parser\ParserManager');
$parserManager->setCache($serviceLocator->get('Your\Configured\Cache'));
```

**Update:**
Okay, we can completely forget about this. I just ran a benchmark with the caching, and apparently Zend\Cache has such a bottleneck that it's not worth using it:

```
Without cache, 10,000 cycles:
0.78266501426697
With cache, 10,000 cycles:
3.2520899772644
```