Metadata collection prevention part 1 of ???.

Crypto requests packets are packets that can be routed by nodes in the
DHT. In this pull request I have merged both Natping requests and friend
requests into one common packet (Crypto request packets). Both these
packets should now only be distinguishable by the size of the data in
them to an outside observer for an example on how to send and recieve
data with these packets see: friend_requests.c

Note that these packets are prefixed with id 32 (friend request packets)
which means this change is compatible with the currently running DHT
bootstrap servers.

Also changed small thing in DHT_test.c
Merge branch 'master' of https://github.com/irungentoo/ProjectTox-Core