Update composer.json to use Symfony >=2.2,<3.0

This change also makes sure future stable versions in 2.x series are accepted.
Merge pull request #14 from andrerom/symfony22

Update dependencies to Symfony 2.2
Don't force default values in memcached config
Fixed Memcache server configuration. Now passes server specs as normal arrays and not hashes.
Merge pull request #16 from lolautruche/memcached_configuration_fix

Fixed Memcache driver configuration
Modified composer.json to restore allowance of Symfony Framework Bundle/YAML components at 2.1.x
Merge pull request #17 from jhallbachner/master

Update composer.json for 2.1.x dependencies
Initial README
Merge pull request #20 from inanimatt/master

Add installation and configuration documentation