Added mwalas-r7 to the mail map

.mailmap

@@ -121,6 +121,7 @@ m-1-k-3 <m-1-k-3@github>               Michael Messner <devnull@s3cur1ty.de>
 Meatballs1 <Meatballs1@github>         <eat_meatballs@hotmail.co.uk>
 Meatballs1 <Meatballs1@github>         <Meatballs1@users.noreply.github.com>
 mubix <mubix@github>                   Rob Fuller <jd.mubix@gmail.com>
+mwalas-r7 <mwalas-r7@github>           <marcin_walas@rapid7.com>
 net-ninja <net-ninja@github.com>       Steven Seeley <steventhomasseeley@gmail.com>
 nevdull77 <nevdull77@github>           Patrik Karlsson <patrik@cqure.net>
 nmonkee <nmonkee@github>               nmonkee <dave@northern-monkee.co.uk>