Fix readme to contain up to date information.

Try to better handle various corner cases, make some errors fatal (like
if there is no directory to search for sockets in, it makes no sense to
retry). Also use unsigned long long instead of uint64_t. I have no idea
how big unsigned long long will be, but it will surely handle 32 bits
that it needs to currently.

Server was crashing quite often. Fixed several bugs causing crashes and
made sure that the data provided via CLI are parsed properly. Also
decreased a precision of serial, just to be on safe side as we have no
idea what we can encounter on client side.

Provide meaningful error message if certificate can't be found.

Migrate away from `daf` module and start using `policy` module directly.
This allows us top manage the rules without flushing them whenever we
need to remove a blocked domain. It also provides us with statistics
about blocked domains.

Using zsys_info and adding a verbose mode.

Mainly add Doxygen documentation  for everything important and describe
some high-level concepts. Also some minor polishing has been done in
process, like scoping of variables to avoid the need to document them.

This allows to run both server and client - connect them and distribute
the list. Currently state is more or less proof of concept. It works, if
everything goes well. More error handling and recovery needs to be
added.