[HTTPS-E Rulesets] OpenDNS: cdn-blog.opendns.com needs fix

[Christopher Liu]

To whom it may concern:

Within the last few days, the OpenDNS blog (blog.opendns.com) started
using cdn-blog.opendns.com for most images/scripts/stylesheets.

It currently hits the blanket rule for *.opendns.com subdomains,
causing a cert mismatch. It should be rewritten to the bucket,
d1c21ex135qvy3.cloudfront.net

It is probably necessary to move coverage of blog.opendns.com to a
separate ruleset with platform="mixedcontent".

Thank you for your time and help
C. Liu