Feature/bolt cache

Hi

I have updated the bolt cache class to extend \Doctrine\Common\Cache\FilesystemCache

I have deprecated everything in cache itself in favour of using the doctrine cache functions

$cache->get()  i had to return serialised objects and arrays to maintain unit test compatibility

In future this can easily be refactored to use anything in the https://github.com/doctrine/cache/tree/master/lib/Doctrine/Common/Cache like memcache or reddis