Select SignIn IDP based on the issuer query string argument if present, use the default IDP if not present

- Update SampleApplication and SampleMvcApplication to list all configured IDP:s and link to the login for each of them
- Replace first page in SampleMvcApplication with the more informative first page from SampleApplication
- Configure SampleApplication and SampleMvcApplication to use local idp as primary and stubidp.kentor.se as second idp
- Configure deployment configuration of the stubidp to use different issuer for debug and release deploy to facilitate the above scenario

Fix #2
Merge pull request #79 from albinsunnanbo/2SupportForMultipleIdps

Support for multiple idps