AJAX-ify DNS lookups in standard firewall/filter

The standard firewall log has lookup ability but these open in a new tab/window, they don't show in the log, other places the same IP appears in the log aren't visibly resolved, - basically its begging for AJAX-ing.

This commit is simple, elegant, simplifies the interface, and does the following:

1) Handles AJAX efficiently, and should be pretty robust against untrustworthy data/bad return data
2) Retains a single "Click to resolve" icon (and its "hover" tip) next to each IP
3) On clicking: 
 - *all* visible log occurrences of that IP, whether as source or dest, are suffixed in small with the resolved name (or "Cannot resolve") in <small> font
 - the icons next to all occurrences of that IP are replaced by equivalent "faded" icons, and the onclick action removed, for visual guidance
4) The replacement uses standard jQuery, so even on a log of several thousand, the click response is almost immediate.
5) The log looks pretty elegant done this way - it doesn't "fill up with junk" in order to show the resolved lookup, and it's simpler and easier than the current version. 

No obvious drawbacks.

(I haven't done this for the dynamic or summary logs - I think the dynamic one could scroll too quickly for individual "item by item" to be useful)