daemon: account maintenance regression

Issue generated from Tuleap's migration script. Originally submitted by: Guillaume Roguez (guillaume)

Migration/Maintenance system is broken: not able to recreate a new device if ring_device.* files missing (ex: filesystem corruption).

Was tested on GNU/Linux-GNOME and Win32 platforms, using lasted sources.
I only indicate GNU/Linux-GNOME below.

* Environment:
daemon: 1ed6a0fe video: disable auto quality by default
lrc: 68c8ad0 AccountModel: separate selected and chosen account
gnome:

* Reproduce steps:

• Create a new ring account
• stop ring
• delete ring_device.* files associated to this account
• restart ring

* Expected result:

• the client ask for the password
• the client shows the normal screen after correct password given, with new ring device generated

* Actual result:

• the client loops in password asking