AngularJS: relooking of spinner directive

Change-Id: I4b209c042783bb1c5b7ee98258d257d7818452c5
Reviewed-on: http://review.couchbase.org/40698
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>