ICA WinCardCore implementation

This gem implements the WinCardCore API from ICA

Surface

The gem exposes two Rack endpoints that can be mounted in the parent application:

ICA::API is the Grape-based API itself. It can be mounted either inside a parent Grape API or stand-alone.

ICA::Admin::Engine is a Rails engine that provides an administrative interface. It should be mounted in the administrator-restricted part of the host application.