Merged chap_fondements_cubicweb and chap_bases_framework_cubicweb as they were both describing differents aspects of CubicWeb framework.
Replaced original content of mise_en_place_environemment that was by mistake erased and replaced with chap_migration content.
Splits main content in two chapters : what is required to know to develop an application, and the other describing more as a reference others specific functionnalities.