feature request: show thousands separator and percentage for stats

[cachho]

Right now we have:

Difficulty                 1319321123
Height                     102392 
Target Height              3082454

From this it's hard to read how much you have synced.

I'd like it to be something like this for readability.

Difficulty                      1319321123
Height                             102,392 
Target Height                    3,082,454
Sync Percentage                       3.3%

So:

• add a percentage
• text right
• thousands separator (could also use toLocaleString())

[jnbarlow]

I like it. let me see what I can do :)