more logs when "Failed to post results"
more logs when "Failed to post results"

in some runs we get warning:
[01/Jan/2016 21:24:20] WARNING - Failed to post results, No JSON object could be decoded

it would be good to print the benckmark value

Change-Id: I4e61cac555a02c90dcbaf7ec6ab1d53f23d98b37
Reviewed-on: http://review.couchbase.org/58207
Reviewed-by: Eric Cooper <ec84189b94eebf6f3016fe0c016fdbc623489ae7@gmail.com>
Tested-by: Andrei Baranouski <f6b50d8f3f8d6abadc89468769320bb7ef9099f0@gmail.com>

pavel-paulau/perfrunner,couchbase/perfrunner,couchbase/perfrunner,EricACooper/perfrunner,couchbase/perfrunner,EricACooper/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner,pavel-paulau/perfrunner,couchbase/perfrunner,pavel-paulau/perfrunner,dkao-cb/perfrunner,couchbase/perfrunner,dkao-cb/perfrunner,EricACooper/perfrunner,EricACooper/perfrunner