Add 'x_auth_access_type' parameter for Twitter to change the access level of an application

[Diegslapasteque]

Hey,

I use Socialite on my app and I notice that the 'x_auth_access_type' parameter for Twitter was not handle in your package.
This parameter can be used to define the access level of the application. Here is the documentation about the Twitter request_token endpoint.
I'll need to open a pull request on Socialite as well to handle this modification.

I'm open if you have a better implementation for this that can be handle by Socialite natively.

[ZekLouis]

Same issue here, would be very useful for us too !

[bencorlett]

Thank you! This looks really neat.