Validation and UI improvements of the Advanced configuration screen.

In 4.4 we added a page to let system admins change advanced application properties (such as the project keys regex). This is good in that it gives more power to the system admin.

This is bad because it doesn't help keep the admin from messing the system (which a bad regex will do in many subtle and confusing ways).

We need to find a way to validate:

the project key regex. My current thinking is it run the regex against:
existing project keys. they should all match the regex)].
project keys that would be a problem for JIRA (eg. ending in a dash, other punctuation in the project key, not starting with an alpha etc). None of these should match the regex.
The date and date&time fields. The problem being the javascript and java patterns must match the same date format.
I am not sure the best appoach for this yet.
While we are playing with this page I would like to work on the UI to provide hints as to what is editable, how to edit it, and when it has been successfully edited (in the hopes of expanding this table to be used on the general configuration later). We should look and see if the restful table is a good drop in replacement or not.