Improve font deployment

[delucis]

With the update checking introduced in 1.8.0, WordPress can download and install the most recent new version of the theme directly from GitHub. 🎉

However, the zip downloaded from GitHub does not include the necessary font files, which means each one-click update has to be followed by FTP-ing the fonts into place (if one even has FTP credentials).

There has to be a better way.

[delucis]

Using automated deployment from Travis CI, theme archives will be available at version-specific URLs, e.g.:

https://github.com/HGNM/hgnm-2014/releases/download/v1.8.1/hgnm-2014.zip