Remove Answer<'static from route implementation

[sergeysova]

We can generate type alias. Instead of this:

pub async fn route(
    app: web::Data<crate::App>,
) -> Answer<'static, register_request::Response> {

Generate result type:

pub async fn route(
    app: web::Data<crate::App>,
) -> register_request::Answer {

[sergeysova]

ref #17