ASTRID architecture

Specification of the ASTRID architecture, to be used as a blueprint by the other WPs to define and develop the components under their responsibility. This will be a live specification, initially defined at M10 and then continuously updated according to the progress of the technical activities, using a spiral-like approach where the initial specification is coarse and at high-level and, as the time passes, gets refined with more details. The final architecture will be captured by D1.3.