Add pgsql_wrapper into the extras requirements for the PostgresMixin
Updates to the base Consumer

- Rename back to Consumer
- Remove the PublishingConsumer from base
Add AMQP_PROPERTIES and AMQP_INTEGER_PROPERTIES

- These are used by multiple modules
Update the mixing documentation
Include the various non-extras mixins to the __init__
Updates to AttributeConsumer

- Rename to AttributeAssignmentMixin
- Move properties to be based off of data.AMQP_PROPERTIES
Base Mixins

Implement a base Mixin for all other mixins to implement and move the PublisherMixin here from consumer.
Update the content mixins, renaming them, making specific types of mixins for encoding/decoding, serializing/deserializing
Update the MsgPackMixin
Add RPC mixins to the list