change DESIGN.md to not have cfssl as service
change DESIGN.md to not have cfssl as service

This removes from the DESIGN.md diagrams the remote call to a cfssl
service. cfssl is being used as a library now.

Also, mention the generation of the first OSCP certificate but not the
storage of it to line up with other usage in the doc.

ibukanov/boulder,tomclegg/boulder,sophie-h/boulder,benileo/boulder,ZCloud-Firstserver/boulder,r0ro/boulder,KyleChamberlin/boulder,hlandauf/boulder,KyleChamberlin/boulder,modulexcite/boulder,lucasallan/boulder,jfrazelle/boulder,lucasallan/boulder,bmw/boulder,lucasallan/boulder,modulexcite/boulder,bmw/boulder,hlandauf/boulder,r0ro/boulder,jfrazelle/boulder,jfrazelle/boulder,kuba/boulder,josephyzhou/boulder,josephyzhou/boulder,ibukanov/boulder,julienschmidt/boulder,mommel/boulder,hlandauf/boulder,lmcro/boulder,mozmark/boulder,devpaul/boulder,mozmark/boulder,jgillula/boulder,devpaul/boulder,sophie-h/boulder,mommel/boulder,kuba/boulder,jcjones/boulder,mozmark/boulder,josephyzhou/boulder,patf/boulder,julienschmidt/boulder,jcjones/boulder,benileo/boulder,ZCloud-Firstserver/boulder,tomclegg/boulder,mommel/boulder,devpaul/boulder,letsencrypt/boulder,mehmooda/boulder,deserted/boulder,letsencrypt/boulder,lmcro/boulder,kuba/boulder,deserted/boulder,jcjones/boulder,jgillula/boulder,kuba/boulder,letsencrypt/boulder,patf/boulder,mozmark/boulder,jgillula/boulder,sophie-h/boulder,KyleChamberlin/boulder,jmhodges/boulder,julienschmidt/boulder,benileo/boulder,josephyzhou/boulder,postfix/boulder,postfix/boulder,ZCloud-Firstserver/boulder,jsha/boulder,mehmooda/boulder,devpaul/boulder,mehmooda/boulder,postfix/boulder,KyleChamberlin/boulder,ibukanov/boulder,deserted/boulder,lmcro/boulder,jmhodges/boulder,patf/boulder,lmcro/boulder,benileo/boulder,jcjones/boulder,jmhodges/boulder,jsha/boulder,patf/boulder,bmw/boulder,postfix/boulder,modulexcite/boulder,julienschmidt/boulder,mehmooda/boulder,r0ro/boulder,r0ro/boulder,jgillula/boulder,tomclegg/boulder,jfrazelle/boulder,mommel/boulder,jmhodges/boulder,hlandauf/boulder,jsha/boulder,modulexcite/boulder,ZCloud-Firstserver/boulder,deserted/boulder,tomclegg/boulder