Ers into develop

The Ers branch substitutes the current logging system, to use the ERS-API for error handling and reporting. This allows creation of custom issues, which can be thrown as exceptions, and also supports exception chaining for detailed error information. The ERS-API handles all the functionality of the former logging system, including seperate log levels for core and modules, without the use of HEDLEY, but by setting environment variables. The ERS-API also writes to the ZMQ-sink passing a the issues in json format.

This version of DAQling uses the ERS-API, but has removed dependency on HEDLEY and spdlog.