watcher:  restart after command only if running

After processing a command from the client, only restart the watcher if
the watcher was already running.  This allows the client to first set
options on the watcher before starting it.
Merge pull request #654 from jsbronder/restart

watcher:  restart after command only if running
Add helper methods to CircusPlugin for parsing the received data

Before this change, each plug-in had to split data into "topic, msg", the u(topic).split('.'), then implicitly know that topic_parts[1] was the watcher name and topic_parts[2] was the action. Also, if the plug-in wanted to parse the msg portion, it needed to import zmq.utils.jsonapi. Not at all obvious to a plug-in writer.
Change buffering in docs to 1 since 0 doesn't work for text files on Py3
Fix line length for flake8
Merge pull request #657 from scottkmaxwell/parsing-helpers-for-plugins

Parsing helpers for plugins
Correct a typo in hooks' documentation
Merge pull request #659 from Khady/patch-1

Correct a typo in hooks' documentation
watcher:  drop log message from error to debug

If a restart or stop is issued via circusctl, it is perfectly reasonable
that a watched process will already be reaped.

See https://github.com/mozilla-services/circus/issues/658
Added after_spawn hook with tests and docs

I also had to fix the logic for before_spawn. Returning False prevented the process from running, but did not set the watcher to 'stopped' if all spawns were prevented, causing manage_processes to try to relaunch it again immediately.
Handle refused connection more immediately
Remove unnecessary socket constructor
A bit more detail about the uWSGI example
did you mean 0mq 2.1.10?
Merge pull request #664 from johnnoone/fix-dependancies

did you mean 0mq 2.1.10?
fixed shell argument parsing
fix flake8
Merge pull request #666 from johnnoone/shell-failure

fix shell=True
Merge pull request #663 from scottkmaxwell/after_spawn_hook

Added after_spawn hook with tests and docs
Merge pull request #660 from jsbronder/lower_reap_error

watcher:  drop log message from error to debug