- removes wkhtmltopdf entry ;
  as cloudooo has a hack to use wkhtmltopdf
  (see 8b49da34 in cloudooo repository)

- removes useless mimetype entries ;
  OnlyOffice entries were also defined in the generic_cloudoo recipe.

This violates "instanciation happens offline" rule and project which
initiated this need do not use it anymore.

fixing segmentation fault on css opacity rendering

/reviewed-on nexedi/slapos!81

update cloudooo configuration as well.

This use haproxy and configureable amount of cloudooo instances (via parameters).