Increase default arp sysctl values

[nephomaniac]

Default sysctl ARP limits should be increased.

It looks like gc_thresh defaults are 128, 512,1024 (shown below).
Suggesting the cookbook contains default attributes which use the values: 1024, 2048, 4096.
Also suggesting the CB includes gc_stale_time and gc_interval attributes.

[root@euca]# sysctl net.ipv4.neigh.default.gc_thresh1
net.ipv4.neigh.default.gc_thresh1 = 128
[root@euca]# sysctl net.ipv4.neigh.default.gc_thresh2
net.ipv4.neigh.default.gc_thresh2 = 512
[root@euca]# sysctl net.ipv4.neigh.default.gc_thresh3
net.ipv4.neigh.default.gc_thresh3 = 1024
[root@euca]# sysctl net.ipv4.neigh.default..gc_stale_time
net.ipv4.neigh.default..gc_stale_time = 60
[root@euca]# sysctl net.ipv4.neigh.default.gc_interval
net.ipv4.neigh.default.gc_interval = 30