Doctrine resource events

This PR fixes issue #77
Documentation about the events are added to the documentation / comments.

Notes:
1) 
**Merge order**: dev-master, #76, #79 
This will give some merge conflicts. I fixed them here:
https://github.com/veewee/zf-apigility-doctrine/commit/0d18762bd6cfa9c2642bebb8fb3bd1212bcb3823
I don't expect issues with: #73  

2)
When these changes are merged, it is possible to clean up the fetchAll method.
The shared listener can now be added as a default listener aggregate through the `attachDefaultListeners`, which will be faster and cleaner.