Add .mailmap

Copied from gerrit and trimmed to removed unnecessary lines.

Change-Id: I3eb8e0efabe5f92e461388b0e9bf5f882a2b3282

.mailmap

diff --git a/.mailmap b/.mailmap
new file mode 100644
index 0000000..154b9bb
--- /dev/null
+++ b/.mailmap
@@ -0,0 +1,5 @@
+Adrian Görler <adrian.goerler@sap.com>        Adrian Goerler <adrian.goerler@sap.com>
+Edwin Kempin <edwin.kempin@sap.com>           Edwin Kempin <edwin.kempin@gmail.com>
+Saša Živkov <sasa.zivkov@sap.com>             Sasa Zivkov <sasa.zivkov@sap.com>
+Saša Živkov <sasa.zivkov@sap.com>             Saša Živkov <zivkov@gmail.com>
+Shawn Pearce <sop@google.com>                 Shawn O. Pearce <sop@google.com>