Sync contracts gp

Again a huge PR. We will do some functional testing during this week. This code should be used for next stable version (will be merged in branch 7.0), and will be used as soon as we are ready. Changes include:

- New Child State Workflow
- Child exit reasons (prepared for webservice retrieval, but the webservice is still in beta mode)
- Module sponsorship_sync, to synchronize with GP.
- Remove sponsored children from the website automatically
- Menus reorganization
- LSV,DD Communication improved
- Improves different search view to add filters and search options
- Contract origins
- End sponsorship wizard to include reasons of ending and updating child status.
- CRM_compassion, for managing events and projects.

With this release, users will create/edit and end sponsorships from Odoo. Accounting will be made in Odoo, as well as events planning. Everything else is still available in GP, and the two programs will work together.

PS: I took care not to include translations in the PR, they will come in a separate PR.

I guess it's an Odoo standard... these methods are only called by the workflow. If you look at other objects it is also made this way (invoice_paid, invoice_cancelled, ...)