Add some locations to the testimonials list.
Implement stupid sandbox.

The stupid sandbox is an insecure sandbox, meant to be used for testing
CMS in environments where you can't use other sandboxes (for example
because of wrong kernel version, missing kernel options, lack of
superuser rights).

It must not be used in real contests. You can enable it setting the
hidden config option "sandbox_implementation" to "stupid".

This stupid sandbox is probably still a bit buggy. I hope, at least,
not to have introduced regressions in isolate.
SS: use the new exc_info argument in logger
Fix a couple of docstrings
SS: use 'requests'
SS: make better use of gevent

Use a different greenlet to manage each RWS, to parallelize the
requests. Hence a "slow" RWS will not hold updates to a "fast" RWS.
SS: small improvement in encode_id
SS: improve some logging