v0.3-beta

• Added guilds.members.read support
• Added refresh_token(), the ability to refresh an access token.
• Removed gdm.join as it is no longer supported by discord
• exchange_code() now returns a access_token object. (this will break all code using an older version)

Access tokens have three properties:

• access: token_instance object (exchange_code() used to return a token_instance object)
• expires: how many seconds until access will expire.
• refresh_token: this can be used with refresh_token() once access has expired