Add trait

Hi everyone,

First of all, happy new year, and I hope this year will be successful for all of you and that we still will be able to make awesome modules together!

I'm right now in a need of SlmQueueSQS, and I'd like to use the module asap. However the wait of the 0.3 branch is too long, so I decided to invest time this week, hopefully being able to tag 0.3 in the next days, and SlmQueueSQS immediately after. iirc SlmQueueDoctrine and SlmQueueBeanstalk were nearly ready too!

This PR removes the Version class (it was a pain to maintain and has no use), and also removes the ProvidesQueue trait in favor of a QueueAwareTrait to be consistent.

As 0.3 already contained a few BC, this should not be a problem. Speaking about BC, I personally dropped support for PHP 5.3 in all my modules. SlmMail would already benefits it from the JsonSerializable interface and all the syntactic sugar. What about making SlmQueue 0.3 PHP 5.4 only?

ping @juriansluiman and @basz

Let's make SlmQueue 0.3 happen this week! :D