Added contract id verification. (#180)

* Added contract id config.
* Verify contract id with user/peer challenge.
* Updated cluster scripts.
* Updated node client lib for contract id verification.

test/local-cluster/cluster-create.sh

@@ -73,6 +73,7 @@ do
     
     # Update contract config.
     node -p "JSON.stringify({...require('./tmp.json'), \
+            contractid: 'dummy', \
             binary: '$binary', \
             binargs: '$binargs', \
             appbill: '', \

test/vm-cluster/cluster.sh

@@ -346,6 +346,7 @@ do
 
     # Merge json contents to produce final contract config.
     echo "$(cat ./cfg/node$n.cfg)" \
+        '{"contractid":"dummy"}' \
         '{"binary":"/usr/bin/node"}' \
         '{"binargs":"'$basedir'/hpfiles/nodejs_contract/echo_contract.js"}' \
         '{"peers":'${mypeers}'}' \