Wrote tests covering HttpAdapter
Wrote tests covering HttpAdapter

- Test that it returns a GuestIdentity if no Authorization header is
  present.
- Test that it returns boolean false if an invalid Authorization token
  is present.
- Test that it returns an AuthenticatedIdentity if the Authorization
  token is valid.

qapa/zf-mvc-auth,eoko/zf-mvc-auth,jonday-mayden/zf-mvc-auth