Implement Procative Authorization

[johnmanning72]

No description provided.

[jmillan]

Thanks @johnmanning72,

I'll review it in detail in the following days.

I'll most probably do some modifications to comply with the repository format and usage.

Thanks!

[jmillan]

NOTE 1: Since there is a single key in the auth map it makes no sense for it to be a map.

Also, @johnmanning72 , does this work only for REGISTER? Does it work for subsequent N REGISTER without being challenged? Does it also work for INVITE and other methods?

NOTE 2: I'll need to prepare real environment before merging this, so it wont be immediate.