get date codecs working
nicer try.js

```
% node try.js
--> jsonml-xml-codec 2 json-codec
input:      <foo>bar</foo>
a2b(input):   ["foo","bar"]
b2a(a2b(input)):  <foo>bar</foo>
SUCCESS ✓

--> unix-time-date-codec 2 iso-date-codec
input:      1398408254
a2b(input):   2014-04-25T06:44:14.000Z
b2a(a2b(input)):  1398408254
SUCCESS ✓

```