1. Changes to share karma config settings across different targets (one target for each feature)
Command to run test cases for a feature:
$cd contrail-web-controller/webroot/test
$grunt karma:monitor_infra  //It will run all the test cases for Monitor Infrastructure
$grunt karma                //With no sub target,it runs the test cases across all features

2. Changes to use sinon npm module instead of including "sinon.js" file
Merge pull request #170 from nagakiran/unittest

simplify unit test targets