Allow remote imports without checked names

By default all names are checked (LUCreateInstance, name_check). In some
cases it can be useful to disable this check, but doing so was not
allowed for remote imports. One should be aware, however, that using
this feature can lead to rename script failures when importing a remote
instance without the proper name, e.g.:

“Failed to run rename script for inst1 on node node3.example.com: OS
rename script failed (exited with exit code 1), last lines in the log
file:\nCannot rename from inst2.example.com to inst1:\nInstance has a
different hostname (inst2)”

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>