ca-certificates: remove CNNIC root CA

Issues with this CA had been raised before, so after this incident:

http://googleonlinesecurity.blogspot.com.es/2015/03/maintaining-digital-certificate-security.html

I'm blacklisting it.

Build triggered.

Build finished. Result Failed Build results available at: http://jenkins.trisquel.info:8085/job/request-merge-source-builder/107/

mentioned in commit de69e43d