Fix "stg mail" address parsing for hyphen

Fix "stg mail" address parsing for hyphen

From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>

Tried sending an email cc'ing LKML - watched my postfix queue - and saw
kernel@vger.kernel.org as delivery address! What had happened? StGIT didn't like
"linux-kernel" ! Fix the regexp.

I just added an hyphen to both sections (yes, there are plenty of domain names
including hyphens, and I tested the problem there too). Don't know if other
chars are missing.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>