Initial IPVS support code.

The IPVS gateway service will be responsible for creating and deleting
virtual servers on the gateway host based on backend locator information
as well as weight management using nodes aggregated statistics.
Merge branch 'master' into ipvs
Drop network stuff which was moved to Core.

All the network code has been moved to the Core's locator service, it
seems to be the most reasonable place to do service discovery.
Merge branch 'master' into ipvs
Merge branch 'master' into ipvs
Changelog bump.
Merge branch 'master' into ipvs
Added abort to urlfetch methods

In case of socket-only errors like timeout or connection refused
there is no HTTP answer from server. In such cases it's more
sutible to abort the request with error_code == errno.
Added urlfetch::post method to c++ stub
Merge branch 'v0.10'
Changelog bump.
Merge branch 'v0.10'
Drop cocaine::error_code.

Follow the changes in master.
Merge branch 'master' into ipvs
Version bump.
Include now-missing headers.
Drop the Dealer Driver. Cleanup. Changelog bump.
Dependencies bump.