Oauth

Closes #180 (closed) and #197 (closed).

A few things to note. The following environment variables need to be added to make SSO work:

export BIOINTERACTIVE_OAUTH_CLIENT_ID=hhmi_assessment_builder
export BIOINTERACTIVE_OAUTH_CLIENT_SECRET=abc123 // to be reissued by Forum One
export BIOINTERACTIVE_OAUTH_REDIRECT_URI=https://hhmi.cloud68.co/biointeractive-oauth // to be updated with Forum One
export BIOINTERACTIVE_OAUTH_TOKEN_URI=https://www.biointeractive.org/oauth2/token
export BIOINTERACTIVE_OAUTH_API_USER_URI=https://www.biointeractive.org/oauth2/UserInfo
export BIOINTERACTIVE_OAUTH_AUTH_SERVER_URI=https://www.biointeractive.org/oauth2/authorize

Additionally, this variable allows the "Log in with Email" option to be visible:

export CLIENT_SHOW_EMAIL_LOGIN_OPTION=true