Rethink the definition of a packet

[KtorZ]

What we call a packet at the current moment is fixed over time and for every component.
That approach is too both too restrictive and wrong. Packet has to evolve over time and each component is contributing to those changes. At the end (after a handler publish it to an application), a packet should be way more than it was when received by a router.

[KtorZ]

The remark also stands for registrations.
Looking at the broker storage, an entry is defined the following way:

type brokerEntry struct {
    Id      string          
    NwkSKey lorawan.AES128Key
    Url     string         
}

which in itself almost implies an http protocols (through the Url attribute). The abstraction should be raised up a little bit to let the adapter decide completely how to transfer a message given an option param.

[KtorZ]

done cde7515.