document_page porting to odoo 8.0

I started from this branch - https://github.com/savoirfairelinux/knowledge/tree/8.0-document-page - to migrate document_page to oboo 8.0

I used the new API for models and wizards
and 
I removed some parts that I didn't find in the original launchpad repository - http://bazaar.launchpad.net/~openerp/openobject-addons/7.0/files/head:/document_page/