Tweak settings to make ibrowse perform better for this load test

Hi,

Thanks for creating this benchmark. I noticed that ibrowse performs much better if it is setup for the kind of load you are simulating. See results below. Test was performed on dual core machine with an Intel i5 dual core CPU running Ubuntu 12.04. I would appreciate it if you could accept this change, because with this change it is best in class!

```
$ ./run_client ibrowse
Erlang/OTP 17 [erts-6.1] [source] [64-bit] [smp:4:4] [async-threads:10] [kernel-poll:true]

Eshell V6.1  (abort with ^G)
1> Starting 1000 calls (15.339 MB)
1000: 3160 rt, 1778 ct, 57.563 MB (42.225 increase), 0 failures
2000: 3510 rt, 2003 ct, 58.162 MB (42.823 increase), 0 failures
3000: 3870 rt, 2267 ct, 59.026 MB (43.687 increase), 0 failures
4000: 4230 rt, 2542 ct, 59.361 MB (44.022 increase), 0 failures
5000: 4600 rt, 2784 ct, 59.261 MB (43.923 increase), 0 failures
6000: 4950 rt, 3019 ct, 60.007 MB (44.669 increase), 0 failures
7000: 5310 rt, 3278 ct, 60.570 MB (45.231 increase), 0 failures
8000: 5650 rt, 3538 ct, 60.892 MB (45.553 increase), 0 failures
9000: 5990 rt, 3771 ct, 61.261 MB (45.923 increase), 0 failures
10000: 6350 rt, 4017 ct, 61.428 MB (46.090 increase), 0 failures
11000: 6690 rt, 4272 ct, 61.448 MB (46.109 increase), 0 failures
12000: 7040 rt, 4501 ct, 61.419 MB (46.081 increase), 0 failures
13000: 7410 rt, 4735 ct, 58.753 MB (43.414 increase), 0 failures
14000: 7770 rt, 4990 ct, 58.704 MB (43.366 increase), 0 failures
15000: 8150 rt, 5257 ct, 58.546 MB (43.208 increase), 0 failures
16000: 8510 rt, 5505 ct, 58.623 MB (43.284 increase), 0 failures
17000: 8870 rt, 5708 ct, 59.537 MB (44.198 increase), 0 failures
18000: 9210 rt, 5966 ct, 59.444 MB (44.105 increase), 0 failures
19000: 9580 rt, 6243 ct, 59.655 MB (44.316 increase), 0 failures
20000: 9940 rt, 6474 ct, 59.920 MB (44.581 increase), 0 failures
21000: 10280 rt, 6725 ct, 61.379 MB (46.041 increase), 0 failures
22000: 10640 rt, 6971 ct, 60.058 MB (44.719 increase), 0 failures
23000: 10990 rt, 7209 ct, 58.117 MB (42.778 increase), 0 failures
24000: 11330 rt, 7464 ct, 62.406 MB (47.067 increase), 0 failures
25000: 11700 rt, 7723 ct, 61.813 MB (46.474 increase), 0 failures
26000: 12060 rt, 7954 ct, 62.184 MB (46.845 increase), 0 failures
27000: 12430 rt, 8187 ct, 62.299 MB (46.960 increase), 0 failures
28000: 12790 rt, 8416 ct, 62.544 MB (47.205 increase), 0 failures
29000: 13120 rt, 8683 ct, 64.313 MB (48.974 increase), 0 failures
30000: 13500 rt, 8940 ct, 64.163 MB (48.824 increase), 0 failures
31000: 13860 rt, 9189 ct, 62.834 MB (47.496 increase), 0 failures
32000: 14200 rt, 9434 ct, 62.833 MB (47.495 increase), 0 failures
33000: 14560 rt, 9672 ct, 62.159 MB (46.820 increase), 0 failures
34000: 14900 rt, 9915 ct, 62.284 MB (46.945 increase), 0 failures
35000: 15270 rt, 10169 ct, 63.272 MB (47.934 increase), 0 failures
36000: 15630 rt, 10413 ct, 62.987 MB (47.648 increase), 0 failures
37000: 15960 rt, 10644 ct, 63.161 MB (47.822 increase), 0 failures
38000: 16270 rt, 10894 ct, 63.291 MB (47.952 increase), 0 failures
39000: 16600 rt, 11119 ct, 63.152 MB (47.814 increase), 0 failures
40000: 16950 rt, 11360 ct, 63.141 MB (47.802 increase), 0 failures
41000: 17310 rt, 11619 ct, 62.828 MB (47.489 increase), 0 failures
42000: 17680 rt, 11870 ct, 63.042 MB (47.703 increase), 0 failures
43000: 18030 rt, 12132 ct, 63.106 MB (47.767 increase), 0 failures
44000: 18390 rt, 12403 ct, 60.684 MB (45.345 increase), 0 failures
45000: 18750 rt, 12671 ct, 60.878 MB (45.539 increase), 0 failures
46000: 19100 rt, 12921 ct, 63.383 MB (48.044 increase), 0 failures
47000: 19440 rt, 13173 ct, 63.590 MB (48.252 increase), 0 failures
48000: 19790 rt, 13419 ct, 64.157 MB (48.818 increase), 0 failures
49000: 20140 rt, 13653 ct, 63.744 MB (48.406 increase), 0 failures
50000: 20520 rt, 13921 ct, 63.860 MB (48.521 increase), 0 failures
51000: 20860 rt, 14175 ct, 63.845 MB (48.506 increase), 0 failures
52000: 21200 rt, 14421 ct, 63.322 MB (47.984 increase), 0 failures
53000: 21560 rt, 14666 ct, 62.182 MB (46.843 increase), 0 failures
54000: 21920 rt, 14899 ct, 62.165 MB (46.826 increase), 0 failures
55000: 22260 rt, 15149 ct, 62.409 MB (47.070 increase), 0 failures
56000: 22590 rt, 15408 ct, 62.071 MB (46.732 increase), 0 failures
57000: 22940 rt, 15662 ct, 62.581 MB (47.242 increase), 0 failures
58000: 23290 rt, 15915 ct, 62.223 MB (46.885 increase), 0 failures
59000: 23620 rt, 16183 ct, 62.585 MB (47.246 increase), 0 failures
60000: 23960 rt, 16420 ct, 62.596 MB (47.258 increase), 0 failures
61000: 24310 rt, 16664 ct, 62.601 MB (47.262 increase), 0 failures
62000: 24650 rt, 16900 ct, 62.302 MB (46.963 increase), 0 failures
63000: 24980 rt, 17147 ct, 62.871 MB (47.532 increase), 0 failures
64000: 25370 rt, 17434 ct, 62.394 MB (47.056 increase), 0 failures
65000: 25710 rt, 17696 ct, 62.697 MB (47.359 increase), 0 failures
66000: 26050 rt, 17941 ct, 62.368 MB (47.029 increase), 0 failures
67000: 26390 rt, 18205 ct, 62.657 MB (47.319 increase), 0 failures
68000: 26750 rt, 18443 ct, 62.703 MB (47.364 increase), 0 failures
69000: 27110 rt, 18664 ct, 63.004 MB (47.665 increase), 0 failures
70000: 27460 rt, 18899 ct, 62.860 MB (47.521 increase), 0 failures
71000: 27780 rt, 19143 ct, 62.805 MB (47.466 increase), 0 failures
72000: 28110 rt, 19389 ct, 62.873 MB (47.535 increase), 0 failures
73000: 28460 rt, 19639 ct, 60.014 MB (44.675 increase), 0 failures
74000: 28790 rt, 19880 ct, 65.233 MB (49.894 increase), 0 failures
75000: 29160 rt, 20146 ct, 64.682 MB (49.343 increase), 0 failures
76000: 29510 rt, 20399 ct, 65.253 MB (49.915 increase), 0 failures
77000: 29850 rt, 20639 ct, 64.000 MB (48.662 increase), 0 failures
78000: 30200 rt, 20906 ct, 64.994 MB (49.656 increase), 0 failures
79000: 30570 rt, 21176 ct, 64.973 MB (49.634 increase), 0 failures
80000: 30890 rt, 21405 ct, 65.062 MB (49.723 increase), 0 failures
81000: 31250 rt, 21632 ct, 65.313 MB (49.974 increase), 0 failures
82000: 31630 rt, 21860 ct, 65.278 MB (49.939 increase), 0 failures
83000: 31980 rt, 22118 ct, 64.831 MB (49.492 increase), 0 failures
84000: 32330 rt, 22353 ct, 65.017 MB (49.679 increase), 0 failures
85000: 32680 rt, 22613 ct, 66.259 MB (50.920 increase), 0 failures
86000: 33030 rt, 22855 ct, 65.106 MB (49.767 increase), 0 failures
87000: 33390 rt, 23097 ct, 65.226 MB (49.887 increase), 0 failures
88000: 33760 rt, 23335 ct, 67.275 MB (51.936 increase), 0 failures
89000: 34130 rt, 23579 ct, 65.177 MB (49.838 increase), 0 failures
90000: 34510 rt, 23822 ct, 61.586 MB (46.247 increase), 0 failures
91000: 34860 rt, 24083 ct, 61.875 MB (46.536 increase), 0 failures
92000: 35210 rt, 24336 ct, 62.746 MB (47.407 increase), 0 failures
93000: 35580 rt, 24575 ct, 62.402 MB (47.063 increase), 0 failures
94000: 35940 rt, 24815 ct, 62.154 MB (46.815 increase), 0 failures
95000: 36280 rt, 25070 ct, 61.884 MB (46.545 increase), 0 failures
96000: 36620 rt, 25338 ct, 62.032 MB (46.693 increase), 0 failures
97000: 36970 rt, 25586 ct, 63.671 MB (48.332 increase), 0 failures
98000: 37360 rt, 25839 ct, 63.854 MB (48.515 increase), 0 failures
99000: 37710 rt, 26091 ct, 63.788 MB (48.450 increase), 0 failures
100000: 38070 rt, 26348 ct, 63.407 MB (48.069 increase), 0 failures
```