http://en.wikipedia.org/wiki/ISO_8601

With this pattern it matches:
```
2014-05-25T16:45:49 +00:00
2014-05-25T16:45:49 Z 
```
instead of:
```
2014-05-25T16:45:49+00:00
2014-05-25T16:45:49Z
```
which is the ISO format. Remove the space before the `Z`