various fixes for the addwatcher command and rlimit settings

- change the rlimit json value to indicate RLIM_INFINITY to None to
avoid any platform weirdness with using -1 as that value, which
isn't guaranteed. A convenience function in config.py handles that
logic
- have the addwatcher command build an rlimits dict to pass into the
arbiter/watcher in order to get those values actually used (as they
weren't before)
- make sure to catch ValueError in addition to OSError when starting
a process as ValueError will be raised if something goes wrong with
the setrlimit calls, and otherwise we get in a bad process retry
loop that avoids the throttling logic
- add special logic for setting the NOFILE limit that will assume
that the caller wants to use the configured kernel limit if they
pass a null value in order to use RLIM_INFINITY. See the comment
for more details.
Remove timeout in Arbiter._stop

This timeout delay the stopping of the loop by 1s and
doesn't seem to have any justification.
Stop the Stats daemon properly when killed.

The Stats daemon was leaking a socket when killed (after closing
Circus for instance). It was an issue when using an IPC socket for
stats_endpoint, as the socket file was not being deleted.
Don't use patched Thread._stop with python > 2.7 or 3.2
Drop support for Thread._stop patch on Python 3.0 and 3.1

Those versions of Python are not supported by Circus, so we don't
need to have special patches for them.
Make flake8 happy from Python 3
Handle config and instantiate correct class for papa sockets and processes

PapaSocketProxy has a mostly good implementation but PapaProcessProxy is just a wrapper around Process
Fix client test to allow prefix or postfix term characters
For wdir to point to the correct location
Modify Process so it can be a base class and add 'name' as first param
Typo fix.
Merge pull request #849 from zenbum/patch-1

Typo fix.
Refactor Redirector to handle both streams
Enhance output classes to use timestamp from data if present
Fix uwsgi_lossless_reload to handle bad data better
Track whether process output is redirected or not
Initial papa process support
Finish basic papa support
Enhance reliability of uwsgi_lossless_reload
Merge remote-tracking branch 'upstream/master' into feature/fix-rlimits-addwatcher