acu186104 Bump net-dhcp-ruby to 1.3.2

v1.3.2 contains a fix to grab the mac address correctly for the dhcp
packet for CentOS 7, which changed its ifconfig output slightly
Merge pull request #508 from rightscale/ivory_14_24_acu186104_centos7_azure_start_stop

acu186104 Bump net-dhcp-ruby to 1.3.2