make-bcache.c: Added support for storing "label" information for the

make-bcache.c:  Added support for storing "label" information for the
                the devices in the super-block.
bcache.h:       Bring version information to the latest kernel version.
bcache-super-show.c: Add setsize for caching devices. This indicates
                     the number of devices in caching set.

Testing done:

1.0  make-bcache with --label option and checking back to see if
     bcache-super-show shows the devices.
2.0  bcache-super-show does not bail if version is 5.
3.0  bcache-super-show shows the correct setsize.

Change-Id: If0f1ec6204b233b34ff4c8a57a8809d2c8dbe3e3