Remove unneeded ansible.cfg
Remove unneeded .placeholder file
Rename common target to common.yml
Add collected_files directory to handle them
Very huge commit. Too long to comment all changes

 I commit it as it because Cderic needs to work tomorrow

 * 13 roles are fully functionnal:
     - ntp
     - common
     - java
     - ldap
     - obm-conf
     - postgresql
     - obm-cert (+ca included)
     - obm-db-pg (db creation + draft update manager)
     - obm-ui (with ssl)
     - obm-solr (obm-tomcat included)
     - obm-sync (obm-tomcat included)
     - obm-locator
     - obm-satelite

 * All known bugs have been corrected

 * All unneeded files have been removed

 * All rules in these roles can be replayed

 * obm_conf.ini and pg_hba.conf are managed automatically

 * Each task of these roles is tagged with its role name

 * check on change are massively used instead of handlers

 * syntax and structure are harmonized between roles

 * Production inventory now reflects available roles
   ( it is possible to call ansible on only a role, a tag
     or a group if nedded )