Guest access without bearer token

[sekrett]

I would like a configuration option allowing to have a guest access. If no bearer token was sent, then authenticate_and_set_user should just return without any error and current_user would be left as nil. The line to change is this: https://github.com/Gokul595/api_guard/blob/master/lib/api_guard/jwt_auth/authentication.rb#L28

I managed myself to create a different before_action based on authenticate_and_set_resources doing exactly what I want, but a configuration for letting both behaviours would be great. Tell me if you need this in your gem, I will do a PR.

[Gokul595]

@sekrett Getting this feature request for second time. @xxSkyy requested this in an issue #38 few weeks back.

So, I think we can add this option and make this configurable. Please do the change and submit a PR. Thanks.