added initial version of service hook for Robustest

Why We need service hook - 

Our customers use Git as their source code repository and as we are providing visualised bug tracking, Adding git service hook will be great service to our customers. 

About Robustest - 

With RobustTest, you can Create and Manage Manual and Automation Test Cases, Perform Cross Browser Testing, Convert Functional Tests into Regression and Performance Tests. 

For more information do visit http://www,robustest.com or write us @ care@robustest.com or mail me omnarayan@robustest.com

@Caged , @kdaigle   - Please help us to serve our customer better .