Add hamcrest matchers for url

We can use following matchers to stub http request:  

* WhenGet(It.IsRegex(@"/(staff)|(user)s"))
* WhenGet(It.IsWildcard(@"/staffs/?"))
*  WhenGet(It.Is("/staffs"))

Add **When** to support other methods:  

* When(It.IsWildcard(@"/staffs/?"), HttpMethod.Patch)

And it still work if we use previous stub:

* WhenGet("/staff?employeeId=employeeId001")