[feature] permit to use custom header instead of Authorization

[thomasboni]

Permit to use another header than Authorization to retrieve token.

Current and suggested behavior

Current: this module permit only to use the standard header Authorization
Suggested: permit to user to define a custom header name

Why would the enhancement be useful to most users

For example:
I have a Django API which uses this module to manage authentication with JWT. I run this API in 2 environment: stage and production. Both behind a nginx proxy.

• On production: it works perfectly: my client use the Authorization header to give JWT to API
• On stage: I want to protect my stage environment with a password and without any change to API code.
  • I configure basic_auth in nginx which use the Authorization header.
  • Like in production, my API uses the Authorization header.
  • I have a header conflict...

In this example, I want to use a custom header (ex X-Authorization) in order to avoid conflict and provide both header for nginx & api authentication.

Example from stackoverflow: https://stackoverflow.com/questions/22229996/basic-http-and-bearer-token-authentication