Add codebeat badge
Add codebeat badge

Change-Id: If46421c4adcf490d8b6ba94766429a1cd6752317
Reviewed-on: http://review.couchbase.org/67277
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

couchbase/perfrunner,pavel-paulau/perfrunner,couchbase/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,couchbase/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner