Ignore IntelliJ *.iml files

Change-Id: I2997884b7ab1a39177f97310db465bfa64c79c09
diff --git a/.gitignore b/.gitignore
index 47617be..1e10b15 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
 /.buckd
 /buck-cache
 /buck-out
+*.iml