Added max_mem_abs and min_mem_abs to ResourceWatcher
Added human2bytes to utils.py
Added test for max and min abs mem of ResourceWatcher
Added documentation for max and min abs mem of ResourceWatcher
Merge remote-tracking branch 'upstream/master' into ressource-watcher-mem-abs

Conflicts:
	circus/plugins/resource_watcher.py
	circus/tests/test_plugin_resource_watcher.py
	docs/source/for-ops/using-plugins.rst
Fixed flake8 warnings, adpated tests to async architecture
Removed useless backslashes
Merged max_mem_abs and max_mem (same for min)
Rewrote util.human2bytes + unit tests
fixed doc
Fixed if syntax
Polishing code
add a sequential option to the reload command for #646
add basic test
fixed typo
Delete pids that don't have recent stats
Added circus-top CLI argument process-timeout
validPid renamed to valid_pid
Make sure we don't add extra EOLs - fixes #711
no concurrent execution during arbiter restart

An explicit test is needed because the restart()
command is a kind of stop() command. The start after
the stop is made (externally) by circusd for plenty of reasons.

So the restart() command is over before the arbiter is really restarted.
So the classic synchronized decorator is released too early.

see #714
Fix typo in decr command docstring