Add a Message Journal to synapse-edison

[gsteinacker]

In order to understand the behavior of an application, it is very helpful to be able to analyze, which changes to the system lead to the current (or past) state of some entities.
Especially event sourcing architectures promise to improve the traceability of a system, because every state-change is triggered by commands and/or events received by the application. The purpose of this epic is to take the first step by introducing a message history having the following features:

• Add a REDIS implementation of the MessageStore interface acting as a time-series database for messages.
• Adding the capability to view the messages for a given message key that where received by a single MessageLogReceiver.
• Determining the delta between the payload of any two messages for a given message key