Ignore IntelliJ *.iml files

Change-Id: I4183c9a9e2841e40dd977af8212bb6c61bdd3c8a
diff --git a/.gitignore b/.gitignore
index 660ffeb..e42569d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
 /.buckd
 /buck-cache
 /buck-out
+*.iml