contrib: add restbed patch fixing locale issues

On MacOS, if the language is set to one not using dots to separate
integer and fractional part of a number (like french using a comma),
a bad HTTP version is sent when dealing with the name server. It
prevents registering a username and using one to add a friend in the
contact list.

This patch resets the locale to "C" before attempting to convert HTTP
version from a double to a char* thus enforcing the use of a dot in
the request. The locale is then restored to its old value then
preserving any modification done elsewhere.

Change-Id: I5b116294c428f626e03885b54950c868211e587e
Reviewed-by: Philippe Gorley <philippe.gorley@savoirfairelinux.com>