Getting mail for Azure provider fix + tests

Fix documentation for auth_request directive

The correct endpoint is /oauth2/auth

A new tag

Facebook auth Provider

* will not re-prompt if the email permission is denied, or if you previously authorized the same FB app without the email scope.

Add URL fragment to sign-in form

Remove superfluous quotes from config path

github enterprise provider

Cookie secret encoding?

Closes #256 and #166

adding option to skip provider button sign_in page

fix dist.sh compatibility with GNU coreutils mktemp

Resolves this error:

    mktemp: too few X's in template ‘oauth2_proxy’

fix master build by upgrading with supported golang versions

Using -config="path" will make the application try to open paths with the quotes included which is not what is expected.

Fix typo

OAUTH2_PROXY_SIGNATURE_KEY env var, README update

github provider: allow multiple teams

Add GitLab provider

Added SystemD example service file

Fix small typo in README.md.

fixed formatting

Since most people want to run this as a service, having some sort of an
example file is very useful to have.

use Github provider with GitHub enterprise