* fix customer_view role name typo so that it's correctly limited
to for 'subscriberadmin' role
* revert behaviour of get_usr_preference_rs() to return undef if
no preference is found (no access)
* get_usr_preference_rs() now also fetches all internal preferences
for internal work for 'subscriber' and 'subscriberadmin' roles but
they remain invisible for them and not accesible for direct changes
(only when requested by internal logic)
* new get_usr_preference_rs() 'as_admin' parameter that enables
for internal requests to return the preference value for
'subscriberadmin' and 'subscriber' roles, currently used to
show 'lock' status and 'display_name', which are otherwise
inaccessible as those preferences do not have expose_to_customer,
expose_to_subscriber flags
* fix api_prference_defs() correct filtering of preferences for
'subscriber' and 'subscriberadmin' roles
Change-Id: I1a0e51ace1c649f9061deaccb7d6e9f8459f0ed8