close #181

This actually solves only half of the problem, reverting for now.

This reverts commit 8caf9941.

This is a backport from packet-api-rewrite branch (sort of).
The problem is when we add a socket to the set and then do a lengthy
operation (transfer answer), it may be sweeped at the end without a
chance of querying.

- Needed to fix zonestatus command in master scenario
- Added time reset to evsched_cancel function to cover slave->master transition

- just a hotfix, a proper solution is to get rid of zone_contents->zone link, it's not really needed.

refs #187

The purpose is to observe the behavior of 1.4.1 compared to 1.4.0
refs #187

Resizing of thread units on the run is not used nor endorsed,
as it's hard to guess when the specific threads terminate or not.
(They are allowed to run to the nearest cancellation point or finish.)

Closes #184