Specify JWT as authentication type, remove reservation for TOKEN

[chad-earthscope]

Specify JWT, for JSON Web Token, as an authentication type as follows:

AUTH JWT token

which is in addition to the defined USERPASS authentication type.

Also, remove the reservation of TOKEN which is too generic and likely will not ever be used.

[andres-h]

Feedback from proposal team

Agreed

Change of specification

~Type TOKEN is reserved, but not specified.~ → If type is JWT, then argument is JSON Web Token as specified by RFC 7519.

[crotwell]

+1 on change