Add Git mail mapping

Added a Git mailmap (1) file to link to in documentations to allow
contributors to send mails regarding security issues. This prevents
unnecessary overhead of updating all documents when new core team and
members and contributors are added and additionally adds the main
functionality of the file:
Mapping commits when someone uses a different email address.

References:
  (1) https://git-scm.com/docs/git-shortlog#_mapping_authors

Epic: GH-33
Depends on GH-49
Resolves GH-46

.mailmap

@@ -0,0 +1,13 @@
+# Copyright (C) 2017-present Arctic Ice Studio <[email protected]>
+# Copyright (C) 2017-present Sven Greb <[email protected]>
+#
+# Project:    snowsaw
+# Repository: https://github.com/arcticicestudio/snowsaw
+# License:    MIT
+
+# Configuration for Git mail mapping feature to coalesce together commits by
+# the same person in the shortlog, where their name and/or email address was
+# spelled differently.
+# See https://git-scm.com/docs/git-shortlog#_mapping_authors for more details.
+Arctic Ice Studio <[email protected]>
+Sven Greb <[email protected]>