bind-add-zone: add bind zones using pdns_control

Add pdns_control for loading new zones without reloading named.conf.
Zone is added but not loaded, you should do it manually, by querying
something. Beware of cache, it is better to purge it before.
bind-add-zone: Add stress-test for bind-add-zone

Uses dnsperf. See README for details.
bind-add-zone: fix for tests context
bind-add-zone: verbose error message
bind-add-zone: rename test, fix timeout
bind-add-zone: add docs
bind-add-zone: lock reworked. caller of createDomain have to take lock
bind-add-zone: protect file with s_state_lock
improve tsig test
remove option to run with EDNS ping mode, clarified edns-disable option to leave it disabled, and warn if you run with it enabled. Thanks to Marcin Gondek for the suggestion!
fix NSEC wildcard denial
make it possible to run presigned tests against backend of choice or nsd
format test descriptions
start-test-stop code formatting
add bind slave to start-test-stop
Merge pull request #1017 from mind04/tsig

improve tsig test
Merge pull request #1018 from mind04/nsec

fix NSEC wildcard denial
Merge pull request #954 from paboldin/bind-add-zone

BIND backend: Add zones on pdns_control
caveat caller
recursor 3.5.3 docs