Session#topic now returns the parsed response instead of a HTTParty::Response

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Update Readme

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>
Add travis.yml for CI

Signed-off-by: Aymeric Brisse <aymeric.brisse@perfect-memory.com>