do not store kvdb instance (#1482)
do not store kvdb instance (#1482)

when kvdb becomes unavailable, a new wrapper is added to it.
query kvdb instance instead of saving it.

Signed-off-by: ganesh <ba2e4e8b8ab27814a47bf9e6a29ac32f7e70e5f6@portworx.com>
libopenstorage/openstorage,libopenstorage/openstorage,libopenstorage/openstorage