Refactored events constructors to prevent incorrect unserialialization.
interface.Reader bugfixing.

+ Fixed incorrect library calls without open reader.
+ Made 38400/"asio" default prameters.
+ Added explicit error mode to Reader constructor.
Refactored "value" to "amount" in purse.change_value
Optimized transport_card.clear implementation.
/api/card/clear now uses updated transport_card.clear
Reordered api handlers.
Minor fixes.
/api/reader/detect added  + major improvements for version 1.4.2:

+ json format errors are now correctly detected reported via JsonError.
+ list ofrequired arguments for api calls are now being inspected and
checked with MissingParameterError if there is no parameter present in request.
+ implemented /api/reader/detect - api call that discards currently
present readers and looks for available and compatible serial ports. After
that aforementioned ports, sorted by their index, are being used in service.