Ignore IntelliJ *.iml files

Change-Id: I7397e53a9d82137b0669ff47dd36f45b8a056fb7
diff --git a/.gitignore b/.gitignore
index 9c143f3..02bc5a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,4 @@
 /.buckd
 /buck-cache
 /buck-out
+*.iml