Don't associate spares with other arrays during RAID Examine

Don't associate spares with other arrays during RAID Examine

Spares in imsm belong to containers, not volumes, and must go into
a separate container when assembling the RAID.
Remove association spares with other arrays and make Examine print
separate containers for spares.
Auto assemble without config file already works like this. So make
creating a config file and assembling from it consistent with auto
assemble.
With this change, mdadm -Es will add this line to output if spares
are found:
ARRAY metadata=imsm UUID=00000000:00000000:00000000:00000000

Signed-off-by: Oleksandr Shchirskyi <oleksandr.shchirskyi@linux.intel.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>