[Tilesathome] Renrender tileset button

[spaetz]

Due to popular request the tile detail page contains a "rerender" button now. It appears on all pages where it makes sense (ie z>=12) and always requests the default layers with priority 1.

Example:
http://tah.openstreetmap.org/Browse/details/tile/14/13990/8545/

If this works out nicely, I'll see how I can do the same for the "Browse Map statically" page

spaetz