[MERGE] [FIX] [ADD] project, project_issue, portal_project, portal_project_issue...

project: privacy_visibility now has basically 'public', 'employees' and 'followers' possible values.
portal_project: add 'portal' to the privacy_visibility values
- public: everybody see the project and all tasks
- portal: employees see the project and all tasks; portal users see the project and the followed or assigned tasks
- employees: employees see the project and all tasks
- followers: employees see the project if follower and the follower or assigned tasks

portal_project, portal_project_issue: added tests for access rights

bzr revid: tde@openerp.com-20130415083130-buklyo8kdpzrbzb7