The fields follow the basic structure of basic Hashes and Arrays but
provide an interface better suitable for us. Specifically:
* They check and enforce the datatypes for keys and values to be
strictly JSON-conforming. Only the basic data-types are accepted
respectively converted to.
* Hashes only accept String keys.
* Basic values are always frozen.
The Rackstash::Logger class will server as the public main entry point
for users. It will eventually implement the mostly complete interface of
Ruby's Logger.
The idea of Rackstash is the we will allow to buffer multiple log
messages allong with additional data until a combined log event is
eventually flushed to an underlying log target. This allows to keep
connected log messages and data as a single unit from the start without
having to painstakingly parse and connect these in later systems again.
