Better print for debug and log

[Fi3]

When we print hashes, and keys, we should use hex encoded string rather then byte array since are a way easier to read and compare.

In the json MG test would be easier to use hex encoded string rather then byte array as well.

So I propose to:

1. whenever we have a byte array we should print it as an hex encoded string
2. the json parser should be able to parse hex encoded string into hashes keys ecc ecc

[rockcoolsaint]

Is this a project-wide fix or there's a particular file where this occurs? You should probably drop a link to a typical reference file if there are many instances @Fi3