[MERGE] from trunk
[FIX] point_of_sale: removed useless escpos python module & pyusb from hw_proxy module
[FIX] hw_escpos: added pyusb as an external dependency of the module, to prevent it from being installed without pyusb available
[FIX] hw_escpos: added pyserial, pyqrcode & PIL  as external dependencies of the module, to prevent it from being installed if they aren't available
[FIX] hw_escpos: removed PIL external dependency as it is already required by openerp
[FIX] hw_scanner: made evdev dependency optional (obviously it won't work if it's not installed...)
[IMP] project: remove duplicated field complete_name (already present in account.analytic.account)
[MERGE] from trunk
[MERGE] better management for python dependencies of the hardware driver modules