Added RefreshWithAuthentication methods to the basic Api.

Functionality as described here:
"Get the Authenticated Discovery Resource"
https://familysearch.org/developers/docs/guides/api-basics
Merge pull request #4 from CutFlame/RefreshWithAuthentication

Added RefreshWithAuthentication methods to the basic Api.
Added a Timeout property to the BasicGedcomxApi (default 10 seconds).

The Timeout is added to the RestRequests created by the Descriptor in each of the public methods.