[MERGE] Review/Update EDI features for 7.0:

Some EDI features replaced by the improved 7.0 portal (with auth_signup)
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- remove the static export of EDI document and the persistence of these EDI blobs, replaced by the live portal access to the document (via portal module)
- remove all the qweb templates and web controllers that were previously used to give access to the EDI document preview
- preserve the web controllers/URLs that were use for the direct EDI import (so that a document from a 6.1 system can still be imported in a 7.0 system)
- temporarily remove the EDI export UI, replaced for the time being by the portal view. => It is planned in 7.1 to provide a new EDI export system via email notification and attaching JSON EDI blobs to outgoing emails. Thanks to the mail gateway integration and a whitelist/certificate system it will be possible to setup end-to-end B2B EDI automation.
- EDI email notifications now integrated in Sales/Invoicing flows via an explicit "Send by Email" step
- PDF version of the document now sent along with the notification (instead of a simple link to view it)
- Portal signup link integrated in this notification when the portal module is installed (via glue module sale_portal)

Online Payment (Paypal) features preserved in a different form
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- as the EDI preview was removed, the payment button was moved to a new banner in the portal view of relevant documents, as follows:
- addition of a new portal.payment_acquirer model to define online payment gateways such as Paypal, Google Checkout, etc. (Paypal included by default)
- new payment banner added to the portal form view of Sale Orders and Customer Invoices, allowing online payment via defined payment_acquirers
- new settings item in Settings>Invoicing>Banks&Cash to make the payment banner visible to all employees as well (normally it's only visible in the portal)

+ minor cleanup and removal of deprecated fields

bzr revid: odo@openerp.com-20121120170915-cmb77iubyrwmib2l