Checking in changes prior to tagging version "0.6.4".

Changelog diff:

diff --git a/History.md b/History.md
index 1cded34..0123ea0 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,6 @@
+0.6.4 / 2014-01-05
+  * Fix plv8x not bootstrapped when client flag is specified
+
 0.6.3 / 2013-12-18
   * Allow options in plv8x.new:
     * `client` flag to assume plv8x bootstrapped
export define-schema
Move define-schema into export util