CookieJar header field

[ralpha]

In development a Cookie header was added when CookieJar was present as a FromRequest parameter.
But this gave issue for some people. The changes has since been reverted.
More info can be found in issue #95.

Code that was reverted in d0a82a0:

impl<'r> OpenApiFromRequest<'r> for &'r rocket::http::CookieJar<'r> {
    fn from_request_input(gen: &mut OpenApiGenerator, _name: String, required: bool) -> Result {
        let schema = gen.json_schema::<String>();
        Ok(RequestHeaderInput::Parameter(Parameter {
            name: "Cookie".to_owned(),
            location: "header".to_owned(),
            description: None,
            required,
            deprecated: false,
            allow_empty_value: false,
            value: ParameterValue::Schema {
                style: None,
                explode: None,
                allow_reserved: false,
                schema,
                example: None,
                examples: None,
            },
            extensions: Object::default(),
        }))
    }
}