Add comment support in JSON.

This isn't strictly JSON compatible, but it is very useful.  Implement
/**/ because it is pretty simple.

Change-Id: Ia277200e43d5a86a4e5ddcc0456c1e220e2b1d75
diff --git a/aos/json_tokenizer.cc b/aos/json_tokenizer.cc
index 38ff4e3..78bf46e 100644
--- a/aos/json_tokenizer.cc
+++ b/aos/json_tokenizer.cc
@@ -13,6 +13,13 @@
     } else if (Char() == '\n') {
       ConsumeChar();
       ++linenumber_;
+    } else if (Consume("/*")) {
+      while (!Consume("*/")) {
+        if (Char() == '\n') {
+          ++linenumber_;
+        }
+        ConsumeChar();
+      }
     } else {
       // There is no fail.  Once we are out of whitespace (including 0 of it),
       // declare success.