configure.ac: small coding style fix
configure.ac: remove --facebook-client-secret option

This is not used anymore
Enable facebook by default
Don't export the methods dealing with the keyring as public API

These are only meant to be used from within the backend and the
daemon.
daemon: Store the credentials in the keyring inside AddAccount

A new argument of type a{sv} was added to the AddAccount method for
passing the credentials to the daemon. This is an API break, but no
should be calling it apart from the backend code implementing
goa_provider_add_account.

This fixes a race between the "account-added" signal being emitted and
the credentials being actually stored.
Update NEWS
daemon: Don't fail AddAccount if the credentials could not be stored

Fixes: https://bugzilla.gnome.org/674165
daemon: Fail as early as possible if the provider is missing
Enable Microsoft Exchange by default
Prepare 3.5.3
Post-release version bump
Port to libsecret
Update NEWS
Updated Slovenian translation
Updated Greek translation
Updated Spanish translation
provider: Put the providers in an order that we recommend

The other way to do it would be to attach priorities while
implementing the extension point, but this is simpler and more
readable.

Fixes: https://bugzilla.gnome.org/678907
Updated Arabic translation
Updated Traditional Chinese translation(Hong Kong and Taiwan)
Updated German translation