MB-100: added lvm diagnostics to cbcollect_info

Change-Id: Ic7967867351dfc1d0f8f4d9599c4fa915c1dac38
Reviewed-on: http://review.couchbase.org/25772
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>