apache-frontend: Extend nginx slave configuration to be possible restrict the access by password and/or address

By default authentification by password is enabled. To disable just pass --enable-auth=false

By default all addresses are allowed. if 'allowed-host-list' is passed we set "allow" to the addresses passed as parameter and deny all the rest.

Note: site_url is not published anymore because it has the same information of url

/reviewed-on nexedi/slapos!175

Further rewrite should be done but at least there's no awk code anymore.

  Apache MPM Watchdog promise was introduced to search apache on
  deadlock state after a graceful reload and kill them after 600s.

  This change prevents the apache lack of nodes after several processes
  get stalled on deadlock.

  This can be used to define minimal metrics to the frontend to
  prevent mpm nodes starvation after gracefull restarts

  Wait for 60 to reload apache configuration in order to accumulate
  several logrotate runs.

  If the amount of slaves are too high, the number of logs are high,
  so the entries on logrotate are also high. So it is enough to DDoS
  with a huge amount of 'kill -1', so delay is the only way to avoid
  to re-implement logrotate existing features.

  Only reload the apache configuration if the the apache configuration
  or the certificates contains a change, else don't reload it.

  Keep a command on bin folder to force reload of configuration in
  case it is required.

The mpc and mpfr component already in the component/binutils.cfg. Remove the duplicate ones.

Update: the test passed. @rafael 

/reviewed-on nexedi/slapos!163

/reviewed-on nexedi/slapos!173

/reviewed-on nexedi/slapos!172

/reviewed-on nexedi/slapos!169

Tests do pass in https://nexedi.erp5.net/test_result_module/20170530-4EB92D8F/view

/reviewed-on nexedi/slapos!168

Enum values are interpreted as strings in the web ui, which makes
impossible to chosse the number of backups.

Also, set the minimum number of backup to 0, as it is now possible.

This fixes the following error:

    slapos-kill: error: unrecognized arguments: -l /srv/slapgrid/slappart38/var/log/neostorage-0.log

certificate-authority software release and stack was renamed to caucase

plus:
- do not fail if ncurses is installed on the system
- enable libmagic
- load share/nano/*.nanorc by default

Needed for receipt_recognition module. It contain the ocropy library and its binarization, segementation and recognition tools, as well as the scipy library containing the ndimage and stats module used in receipt_recognition_module for the binarization and inside ocropy. 

This is separated in 3 commits:
The first one add ocropy and dependancies inside slapos component;
The second one add the ocropy component to stack/erp5 buildout config file, and add gcc to the binaries callable from erp5 (needed by ocropy);
The third  is only required for the module to work without installing the wendelin software.

Edit: To keep discussions posts, i wont rebase in master, to see the rebased final commits: https://lab.nexedi.com/francois.lecorre/slapos/commits/rebased_branch

/reviewed-on nexedi/slapos!153

Ocropy needs one of matplotlib component to be imported during
buildout. This component needs cycler and dateutil

This allows a recipe building python to add custom extra-path

This commit contain modifications that allow ocropy and scipy to be
installed as eggs. Extra ld_path are added to python to allow the former
to run scipy (that needs libstdc++) inside testnodes.

This commit add component needed for Optical Character recognition:
ocropy and its dependancies

The Ocropy egg on Pypi is empty, so this component have to be built from
source. The default neural network model is downloaded from the author
website and installed in python2.7/share/ocropus.

The patch is here for to different thing: one is adding an
OCROPY_MODEL_PATH to be able to specify the position of models, the
other is importing for the first time a module that compile C code from
python, allowing us to have the static library built before runtime and
preventing us from using gcc through zope.

More models are available here:
https://github.com/tmbdev/ocropy/wiki/Models

  If there is no error, the raise can be missleading.

  Allow http2 protocol be enable or disable by default
  Allow set certain configurations for MPM to control the number of process and threads.

Check that backup kvm disk is not corrupted

Pin erp5.util to version 0.4.49, with:

 * process timeout
 * xmlrpclib.Binary wrapping

Whitespaces matter to exporter.exclude:
- patterns must *not* start with a space
- file *must* end with a newline

Also, de-duplicate paths.