Open ID Discovery & Token Passing to Client

Open ID Connect provider configuration is now read, following the
official specification
(http://openid.net/specs/openid-connect-discovery-1_0.html). Name, logo,
client ID, client secret and provider endpoint URL are now read from a
new config file ./etc/oidc.json. Furthermore, added a redirect HTML
response that writes access token to local storage and allows to use
access token with LAS2peer REST API call.