Add sender emails and fixes typo in ldap schema.

Basic mail retrieval functional. (Main email from Mail plugin).

Mail retrieval from DN put in LDAP.
Commit to fix in order to save attribute in ldap.

Adds reference from task mail to the selected users.

Removes requirement for a name within Task Mail name

Add users selection for mail task as well as schedule within
generic page of tasks creation.

Adds mail selector for task mail

Simple commit of the management and two sub class creation.

Mail list will be implemented within Task object

Add invitations fields and verifications of mail list imported.
Adapts the core-fd.schema.

Adds Mail Template invitations first page, no fields yet.
First commit