BOT: Added contributors file

CONTRIBUTORS.md

+# Contributors to OpenFOAM
+
+The following is an list of known contributors to OpenFOAM.
+It is likely incomplete...
+
+## Contributors (alphabetical by surname)
+
+- William Bainbridge
+- Gabriel Barajas
+- Kutalmis Bercin
+- Greg Collecutt
+- Jonathan Cranford
+- Sergio Ferraris
+- Matej Forman
+- Marian Fuchs
+- Pawan Ghildiyal
+- Chris Greenshields
+- Bernhard Gschaider
+- Andrew Heather
+- David Hill
+- Mattijs Janssens
+- Andrew Jackson
+- Hrvoje Jasak
+- Alexander Kabat vel Job
+- Thilo Knacke
+- Tommaso Lucchini
+- Graham Macpherson
+- Alexey Matveichev
+- Karl Meredith
+- Laurence McGlashan
+- Timo Niemi
+- Haakan Nilsson
+- Niklas Nordin
+- Mark Olesen
+- Vaggelis Papoutsis
+- Juho Peltola
+- Johan Roenby
+- Henrik Rusche
+- Bruno Santos
+- Henning Scheufler
+- Prashant Sonakar
+- Hilary Spencer
+- Gavin Tabor
+- Zeljko Tukovic
+- Eugene De Villiers
+- Yi Wang
+- Norbert Weber
+- Henry Weller
+- Niklas Wikstrom
+