[Ready] Deprecate alephant-publisher in favour of alephant-publisher-queue

![obligatory gif](http://media.giphy.com/media/11uamggNN7KTsY/giphy.gif)

## Problem

`alephant-publisher` functionality is required on a per-request basis, and the existing queue-based functionality is occupying the general `alephant-publisher` name.

## Solution

The existing queue-based functionality is moving to `alephant-publisher-queue`, leaving `alephant-publisher` deprecated.  This is reflected as a post-install message for the gem, and in the README.