Test: Adding dhcprelay tests.
Added isc-dhcp-server for cord-test container builds.
If cord-test container already exists, refresh using:
 cord-test.py build test

Change-Id: I1aaff75612b7551fc9fd145fe2483ab72b5c3128
diff --git a/Dockerfile.tester b/Dockerfile.tester
index 6cc827b..26ddf33 100644
--- a/Dockerfile.tester
+++ b/Dockerfile.tester
@@ -6,7 +6,7 @@
         unzip libpcre3-dev flex bison libboost-dev \
         python python-pip python-setuptools python-scapy tcpdump doxygen doxypy wget \
         openvswitch-common openvswitch-switch \
-        python-twisted python-sqlite sqlite3 python-pexpect telnet arping
+        python-twisted python-sqlite sqlite3 python-pexpect telnet arping isc-dhcp-server
 RUN easy_install nose
 RUN mkdir -p /root/ovs
 WORKDIR /root