4.0.0

This has some changes related to Mattermost 4.4

BREAKING CHANGES:

• Endpoints moved from team to channels https://github.com/mattermost/mattermost-api-reference/pull/298/files
  • get_public_channels
  • get_deleted_channels
  • search_channels

Added endpoints:

• revoke_all_user_sessions in /users
• disable_personal_access_token in /users
• enable_personal_access_token in /users

Also, you can now access the api endpoints directly,
without using Driver.api['endpoint'], instead you can
Driver.users.get_user('me').
Both ways are working, so no breaking change there.
Related Issue for this: #5