Add various web font formats

This makes sure Grumpy can be used in all modern browsers.

Generated using <http://www.fontsquirrel.com/tools/webfont-generator> using the following very conservative settings (I wanted to stick to the original as closely as possible):

```
# Font Squirrel Font-face Generator Configuration File
# Upload this file to the generator to recreate the settings
# you used to create these fonts.

{"mode":"expert","formats":["ttf","woff","eotz"],"tt_instructor":"default","fix_vertical_metrics":"Y","fix_gasp":"xy","add_spaces":"Y","add_hyphens":"Y","fallback":"none","fallback_custom":"100","options_subset":"basic","subset_custom":"","subset_custom_range":"","subset_ot_features_list":"","css_stylesheet":"stylesheet.css","filename_suffix":"-webfont","emsquare":"2048","spacing_adjustment":"0"}
```
Done, thanks!