the resolution driver now correctly fetches keys,
and the zonecut lookup should find closest TA,
then the validation module should have all the
information needed for simple validation

the only flag supported now is the KR_REQ_DNSSEC,
which indicates that the caller wants a secure answer

this can coalesce sends/writes in future versions of libuv

this fixes an issue with libuv sometimes crashing with mismatching number
of descriptors with REUSEPORT

Tests wrapped

See merge request !15