Make SampleMvcApplication point to local StubIdp

Pro: This makes it easier to get the sample application started
Con: It is harder to understand the config file when the host name is
not sensible
Merge pull request #63 from albinsunnanbo/MakeSampleApplicationPointToLocalIdpStub

Make SampleMvcApplication point to local StubIdp
- This makes sense for now, when the stubidp follows the ACS in the AuthnRequest the sample app should point to http://stubidp.kentor.se instead.