Makes repository health check buttons adopt the standard button styles

Before:
![screen shot 2014-11-18 at 11 20 13 am](https://cloud.githubusercontent.com/assets/186715/5094333/f2e9b41e-6f14-11e4-91c3-c3e2fa3b166e.png)

After:
![screen shot 2014-11-18 at 11 18 33 am](https://cloud.githubusercontent.com/assets/186715/5094334/f5d063b2-6f14-11e4-989f-95278cad7711.png)