Add support for -no-CApath and -no-CAfile options

For those command line options that take the verification options
-CApath and -CAfile, if those options are absent then the default path or
file is used instead. It is not currently possible to specify *no* path or
file at all. This change adds the options -no-CApath and -no-CAfile to
specify that the default locations should not be used to all relevant
applications.

Reviewed-by: Andy Polyakov <appro@openssl.org>