API: Recursor: fix initialization of recv buffer

Fixes Coverity CID 1194782.
Initialize d_server

Fixes Coverity CID 1194781.
Initialize AddressFamily for slave sockets

Fixes Coverity CID 727958.
Merge pull request #1349 from zeha/api-bugfixes

Fix (possible) bugs in (Recursor) webserver
API: add api-readonly to Recursor
API: don't add priority to content field on save

We need the prio in content for verification purposes, but for storage
it needs to stay in rr.priority. Adds a test for this.
now, I'm not one to get OCD over things, but that log message about stats based on 1801 seconds got to me. 1800 now.
we reinitialized all our statistics function for each rec_control or even API call, which was wasteful.
needs misc.hh, normally already happened to be included
remove silly enum for AF_INET and AF_INET6 and in the process discovered auth webserver.. was IPv4 only
broke our socket stuff as part of our cleanup - spotted by Christian Hofstädtler
remove old enums
remote enum for socket
fix enums in commented out code
further enum fixes
even more enum
implement built-in statistics dumper using the 'carbon' protocol, which is also understood by metronome
ship carbon files in recursor tarball
add support for carbon-ourname to override our hostname for carbon reporting if needed
Merge branch 'api-recursor-readonly' of github.com:zeha/pdns into zeha-api-recursor-readonly

Conflicts:
	pdns/pdns_recursor.cc