Add .gitignore

Change-Id: I4c5f8185510f8f0255f10ab1f92b7a49451c44a4
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5b6a065
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.Rproj.user
+.Rhistory
+.RData
+.Ruserdata