lump the header push() with the other one for a 10% speedup

before:

$ ab -c 100 -t 5 http://localhost:5000/ 2>/dev/null | grep
'Requests per second:'
Requests per second:    1098.74 [#/sec] (mean)
$ ab -c 100 -t 5 http://localhost:5000/ 2>/dev/null | grep
'Requests per second:'
Requests per second:    1185.37 [#/sec] (mean)
$ ab -c 100 -t 5 http://localhost:5000/ 2>/dev/null | grep
'Requests per second:'
Requests per second:    1217.38 [#/sec] (mean)

after:

$ ab -c 100 -t 5 http://localhost:5000/ 2>/dev/null | grep
'Requests per second:'
Requests per second:    1262.69 [#/sec] (mean)
$ ab -c 100 -t 5 http://localhost:5000/ 2>/dev/null | grep
'Requests per second:'
Requests per second:    1296.30 [#/sec] (mean)
$ ab -c 100 -t 5 http://localhost:5000/ 2>/dev/null | grep
'Requests per second:'
Requests per second:    1318.19 [#/sec] (mean)

> (((1318+1296+1262)/3)/((1098+1185+1217)/3)-1)*100
10.742857142857144
take out the stream param
memory usage
onfinish to handle streams properly
0.0.1