Feature/jk shortcuts for wp table

We have the <key><code>j</code></key> and  <key><code>k</code></key> shortcuts (which go through a list). They are great but didn't work for the new work package index list.

This is a thing of the past now! In the following gif, I'm going through the WP list with the <key><code>j</code></key>/<key><code>k</code></key> shortcuts and view the details of a WP through pressing <key><code>enter</code></key>.

![out](https://cloud.githubusercontent.com/assets/206108/3088548/e2d0e57a-e571-11e3-80fa-d91baa6f7e32.gif)