Management of permissions

[monvoisinf]

We need a management of permissions (to do after the issue #20 ) :

• there is a need to think about the management of permissions, knowing that we will have the authentification through LDAP

I suggest some specifications :

• for non authentified people :
  • possibility to read a file only, if it is available for the public
• for registered people
• make a file public
• make a file private
• write / edit a file

[decima]

Read-only mode made in #78