Add checks to assure that a cached certificate is valid for current request

Add checks to assure that a cached certificate is valid for current request

Add checks in Ssl::certificateMatchesProperties to assure:
 - The CN name of the cached certificate matches the requested CN
 - "Not After" and "Not Before" fields of the cached certificate are valid

Ssl::CommonHostName and getOrganization  functions moved to gadgets.cc to allow
use by ssl_crtd daemon