Allow Cache adapter to be a PSR-6 implementation

[Sander-Toonen]

With Symfony 3.1 a whole new range of PSR-6 compatible cache adapters have come to our disposal. Unfortunately the Cache provider in this bundle only accepts caches that implement Doctrine\Common\Cache\Cache and Doctrine Cache has not jumped on the PSR-6 wagon.

With this issue I'd like to open up a discussion how to facilitate the usage of PSR-6 compatible caches. I see a number of possibilities:

• Rewrite Bazinga\Bundle\GeocoderBundle\Provider\Cache to support both doctrine and PSR-6 caches. (Maybe not really a SOLID solution).
• Create a new cache provider for PSR-6 compatible caches alongside the DoctrineCache-only cache provider. (Might add a bit more complexity to the configuration.)
• Use one of the many PSR-6 - DoctrineCache bridges. (Adds a dependency to another package.)
• Do nothing and let the user implement a bridge. (Not user friendly)

Also I noticed geocoder-php/Geocoder#512.
HTTPPlug allows using a PSR-6 compatible cache plugin (http://docs.php-http.org/en/latest/plugins/cache.html) so another option altogether might be to delegate the caching to the Geocoder library itself.

I'd like to hear your ideas.

[Nyholm]

We will be PSR 6 compatible in next version. It should be configurable. I will take care of this the next few weeks

[Nyholm]

I have created #127 which use geocoder-php/Geocoder#717.

Http providers may use HTTPlug to fix cache.

Btw, I use PSR-16, do you think it will make any difference?

[Nyholm]

This is resolved in master.