Analytics: count flat badges requests.

Also, allow extending analytics.

Related to issue #185.
fixed font Dejavu sans

https://github.com/badges/shields/blob/master/templates/default-template.svg#L12
Add support for david
Merge pull request #198 from liuggio/patch-2

fixed font to Dejavu sans
Merge remote-tracking branch 'sebmck/master'
Merge branch 'master' of github.com:badges/shields
Omit trailing whitespace.