new user for single instance created, login form is sent as "connect to the device"

If connection failed, request is redirect back to login.
If connection succeed, request is redirect to configure device section.

Missing: flash messages propagation if connection failed, correct layout in configure device section.
propagate error on single login fail, single instance login and host could be set in config
disable single instance login by default
parameters.yml should not be versioned (it is generated in installation process from parameters.yml.dist)
Merge branch 'singleInstance', remote branch 'origin'