Ignore IntelliJ *.iml files

Change-Id: I330430909075a5dc751fe18aaa7b5b72940469b1
diff --git a/.gitignore b/.gitignore
index 9ab384b..f69c160 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@
 /buck-cache
 /buck-out
 /bucklets
+*.iml