pulse2: Refs #2149 pulse2-setup traceback without backuppc

Variables who can be None must always be tested like this:

    if myVar is None:
        bla-bla

Ref: http://sametmax.com/id-none-et-bidouilleries-memoire-en-python/
imaging: add missing client name in logs when create image
backuppc: pulse2-backup-servers example URL help string
pulse: remove code duplication for entity list creation
report: initialization of report module
report: Improve python part

Add generic XMLRPC Method to get report datas,
easy way to add report in MMC modules: add your report in a report
directory and that's it.

TODO:
* SQL Schema
* Twisted service to get raw datas of modules
* HTML2PDF integration
* Other ??
report: workaroud for kargs on xmlrpc method
report: main report form