text: Title: Error thrown when following doc example for persisting the token through the consumer’s session property
  Body: **Describe the bug**
  I was following the doc examples for auth to save my access token for a session. However, the code throws an error saying the consumer has no attribute '_Consumer__session':
  
  ```
  AttributeError at /api/v1/jira/issues/
  'Jira' object has no attribute '_Consumer__session'
  ```
  
  **To Reproduce**
  Use the following snippet from the documentation to make a consumer:
  ```pythhon
  class Jira(Consumer):
      def __init__(self, access_token):
          self.session.params["access_token"] = access_token
  
      @get("/rest/api/3/project/search")
      def get_projects(self):
          """Get paginated list of projects accessible by current user"""
          pass
  
  ...
  
  jira_client = JiraConsumer(access_token=access_token, base_url=base_url)
  data = jira_client.get_projects()
  ```
  
  **Expected behavior**
  My custom consumer should get authenticated and I should be able to get data from the endpoint.
  
  **Additional context**
  I am using Uplink with Django. Also, if I supply the access token while creating a Jira client like this it works perfectly.
  
  ```
  jira_client = JiraConsumer(base_url=base_url, auth=BearerToken(access_token))
  ```