Documentation on top on each Jupyter notebook about why and how we use the
environment object.

Adds the astor egg to convert abstract syntax tree objects back to source
code.

@jm noticed downloading arhives in tar.gz format was failing. Details are in second patch.

/cc @lab.nexedi.com

/reviewed-on nexedi/slapos!70

fix publish custom frontend url
simplify monitoring connection parameters

/reviewed-by: TrustMe

This causes Cloudooo to not listen anymore.

/reviewed-on !75

* now glib is built with our own pcre.
* libsigc++, glibmm, pangomm and atkmm are kept in older version because glibmm >= 2.46 requires C++11 compiler.

  The password and username has to be passed to the others instances and used

Define a simple cache implementation using a Dict (Singleton) to prevent call registerComputerPartition
  multiple times over the sections.

/reviewed-on nexedi/slapos!74

  When create a wrapper for etc/service/my-wrapper placing the 2 files
  at the same folder, cause one duplication at the files added to supervisord, so
  always place the python script wrapper at the bin folder of the buildout.