Removed unneeded FixFlags-Property
Removed Singleton/LocalInstance of the Appender

Imho the Hub should have no knowledge about the Appender.
Refactored/Fixed connecting to the hub

It was possible to stay unconnected for the whole lifetime of
the
appender when the SignalR-Host was getting initialized after
the
appender. The proxyConnection-object was not null then, but also not
connected. This had the consequence that the appender never sent
anything to the hub.
Dispose the hub connection
Made hub and group name configurable

This way it's very easy to create a bunch of appenders which can all use
different groups and/or derived hubs