Fix insecure content errors over HTTPS 

When an image URL is secure (i.e. with https scheme), bookmarklet fails to work and JavaScript console show following two errors (at least on Google Chrome):

[blocked] The page at 'https://whatever.jpg' was loaded over HTTPS, but ran insecure content from 'http://cdnjs.cloudflare.com/ajax/libs/require.js/0.26.0/require.min.js': this content should also be loaded over HTTPS.

[blocked] The page at 'https://whatever.jpg' was loaded over HTTPS, but ran insecure content from 'http://jarred.github.com/src-img/js/app/bookmarklet.js?version=0.66': this content should also be loaded over HTTPS.