Add IntelliJ project files to .gitignore

Change-Id: I4457e8b7ad1cf05d23469add6e8d6c2d89e81b99

.gitignore

diff --git a/.gitignore b/.gitignore
index 8b1fe53..60ee4e8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,5 @@
 /eclipse-out
 /gitiles.config
 /.buckd
+/.idea
+*.iml