Global formatter for all metrics

Hi,

First at all, congratulations for this excellent tool. 

In my company we are using kibana for make a bit of bi, so we have a lot of currency related metrics.

I cannot find any way to format the numbers as currency except in the new stats module 
(https://github.com/elasticsearch/kibana/pull/724) 

So i decided to make this PR to provide a way to format every metric in all the panels, 

The code is based in the same numeral library (http://adamwdraper.github.io/Numeral-js/) introduced with the stats panel. A new formatter service and  partial template for the combo was made. 

This is a partial pr (or a PoC) the only working panels now are:
stats
histogram
terms (partial pies are not working)


Some screenshoots: 
![screen shot 2014-01-07 at 19 49 08](https://f.cloud.github.com/assets/1573114/1862236/50246a32-77ce-11e3-96e2-2ebcc10170e7.png)
![screen shot 2014-01-07 at 20 03 03](https://f.cloud.github.com/assets/1573114/1862240/5b486314-77ce-11e3-85f7-e90cec8a726d.png)
![screen shot 2014-01-07 at 19 49 58](https://f.cloud.github.com/assets/1573114/1862245/62d240be-77ce-11e3-8cb7-b59ae75f337b.png)

 Regards