integrate job model into recurring invoice model

[jzarate]

drop the "job" table and add its fields to the "recurring_invoice" table.

also, add the job fields edition on the recurring invoice edition page.

[jzarate]

r348

• job model removed and integrated into the recurring_invoice model
• new widget (sfWidgetFormI18nDateDMY.class.php) created to display days, months or years at will .

[jzarate]

r349

basic editing of some job-like fields within the recurring_invoice:

• day_of_month
• day_of_week
• month

[jzarate]

r358 sfWidgetFormI18nDateDMY refactoring

[jzarate]

r359 full editing capabilities. jquery red labels also visible for the "execution time" combos