Fixes #5229 - Added messages for empty tables in Bastion

When there is an empty table in Activation keys, Gpg keys, Products or Sync plans, message with hint will be displayed. 
This is shown if you don't have any products left to add and you are already on the add tab which makes the message confusing.  Sticking with a simply "No products to Show" may be sufficient here.

![screenshot from 2014-08-26 16 23 01](https://cloud.githubusercontent.com/assets/4116405/4051127/cee1d17a-2d5e-11e4-892a-22bb073261fa.png)