use default text rendering rules for historic=* and leisure=sport_centre fix #42

Fixing issue #42. In current master, the names of historic=* and leisure=sport_centre would display at high zoom levels and not use our default node naming rules, as shown in example: 
![selection_025](https://f.cloud.github.com/assets/955351/981275/fad3e2ca-0756-11e3-8589-29ba1d211e36.png)

There's a couple other instances of this occurring, with operator= and capacity= tags. I'll issue those up and write fixes for them in different branches.