Introduction of Environment Variables

Implement single environment variable to configure application. In this case, SAML_HTTPS_OVERRIDE to force https

Refactored code

Refactored code according to code review

Added login_service traitlet to authenticator

Fixes login template issue on jupyterhub. See https://github.com/jupyterhub/jupyterhub/blob/6be3160d7487bb362df7095f24454ef2814951fc/share/jupyterhub/templates/login.html#L16

Added login_url method to SAMLAuthenticator

authenticator.login_url() needed by Jupyterhub to figure out what the login url is from the login template (see https://github.com/jupyterhub/jupyterhub/blob/6be3160d7487bb362df7095f24454ef2814951fc/jupyterhub/handlers/login.py#L99)

Fixed https bug

Prior to this version, if the IdP was sending a POST to https://:/hub/acs, the handlers.get_request function would encode that as http. This update fixes that bug to detect POST https correctly.

Fixed dependencies in setup.py

install_requires field now contains all the dependencies for this project

First test release

0.1.1

Updated & refactored