Don't force text to be black, only toggle bold.

The `bold` function forced text to be black, which didn't look good on certain inverted color schemes. Just forcing text to be bold should be more compatible.

**Before**
![screen shot 2013-12-20 at 12 23 19](https://f.cloud.github.com/assets/1167977/1790040/490601c4-696a-11e3-9386-3cee538a2eff.png)

**After**
![screen shot 2013-12-20 at 12 32 44](https://f.cloud.github.com/assets/1167977/1790049/756d3dfe-696a-11e3-91b2-3ce2a40d993f.png)