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
fixed typo
Disable multicast discovery upon error. Fix #731.
Append virtualenv bin to $PATH.
add TimedRotatingFileStream
filter out FDs that were never registered in the first place in the poller. refs #737
removed one test on TRAVIS
added back handle_callback_exception during the tests, so it breaks immediatly
Merge branch 'master' of https://github.com/DYFeng/circus into DYFeng-master
flake8-ed