Use schemeless href to work over HTTP and HTTPS

Linking to “http:” for Google Fonts prevents the site from working when
loaded over “https:”. By removing the scheme, the browser will use the
scheme over which the parent page was loaded. HTTP and HTTPS will work
fine some googleapis.com works over HTTPS.
Merge pull request #27 from ssorallen/fonts-over-https

Use schemeless href to work over HTTP and HTTPS