update deprecated haproxy configuration options, set values a little lower
add a httpchk line to haproxy to properly test if the couchdb is available
add the useful http-server-close option

set check option on the servers, with a 3 second interval, a one second
fastinter (for flapping) and a one second downinter. Set the number of checks
for failure to be one (so it will take 3 seconds for a node to fail out) and 2
checks to come back