DateTimeType with timezone detection

Hi, 

this patch enables correct reading in different-timezones (eg. in XML from weatherforcast), it falls back to the old parsing without timezone.
Example:
OpenWeather-XML
```xml
<sun rise="2014-03-30T04:58:47" set="2014-03-30T17:48:03"/>
```
This times are in UTC (timezone is omitted)
The item would be converted to the the wrong time: 
```
DateTime ow_sunrise             "Sonnenaufgang [%1$tR]"   <weather_sunrise>  (Wetter) { http="<[openWeatherCache:1440000:XSLT(openweather_sunrise.xsl)]" }
```
see
```groovy
groovy:000> import java.text.SimpleDateFormat;
===> [import java.text.SimpleDateFormat;]
groovy:000> DATE_FORMATTER = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
===> java.text.SimpleDateFormat@6b2ed43a
groovy:000> sunrise = '2014-03-30T04:58:47'
===> 2014-03-30T04:58:47
groovy:000> DATE_FORMATTER.parse(sunrise)
===> Sun Mar 30 04:58:47 CEST 2014
```
The Correct timestamp would be _Sun Mar 30 06:58:47 CEST 2014_

Via transform, i'm attaching the timezone:
```XSL
<xsl:value-of select="concat(/current/city/sun/@rise, 'UTC')" />
```
now the time is correct:
```groovy
groovy:000> DATE_FORMATTER_WITH_TZ = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssz");
===> java.text.SimpleDateFormat@faabb380
groovy:000> sunrise = '2014-03-30T04:58:47' + 'UTC'
===> 2014-03-30T04:58:47UTC
groovy:000> DATE_FORMATTER_WITH_TZ.parse(sunrise)
===> Sun Mar 30 06:58:47 CEST 2014
```