Allow for other metadata and dates in Footer

With the document footer, we want the ability to pass in other parts of metadata to the Footer. This commit takes the same approach as the metadata blocks - you pass in an other (or other dates) hash and it presents it in the same way.

Screenshot:
![screen shot 2014-12-02 at 11 08 08](https://cloud.githubusercontent.com/assets/449004/5261620/8693a252-7a13-11e4-8688-fb4ba8648883.png)