User protocol upgrade and js client lib. (#191)

* Unified js client lib for browser and nodejs.
* Client lib multiple connections support.
* Implemented server challenge response.
* Contract guid and version validation.
* Server key validation.
* User json message encoding improvements.

test/local-cluster/cluster-create.sh

@@ -84,7 +84,7 @@ do
     
     # Update contract config.
     node -p "JSON.stringify({...require('./tmp.json'), \
-            contractid: 'dummy', \
+            contractid: '3c349abe-4d70-4f50-9fa6-018f1f2530ab', \
             binary: '$binary', \
             binargs: '$binargs', \
             appbill: '', \

test/vm-cluster/cluster.sh

@@ -364,7 +364,7 @@ do
 
     # Merge json contents to produce final contract config.
     echo "$(cat ./cfg/node$n.cfg)" \
-        '{"contractid":"dummy"}' \
+        '{"contractid":"3c349abe-4d70-4f50-9fa6-018f1f2530ab"}' \
         '{"binary":"/usr/bin/node"}' \
         '{"binargs":"'$basedir'/hpfiles/nodejs_contract/echo_contract.js"}' \
         '{"peers":'${mypeers}'}' \