Change default for cert_required

This setting is used to require client certificates, which people likely
do not want by default.
Add an attribute to let the user say the certificate is insecure
webui: Fix setting cert_required
Link ca_certs attribute to cert_required in the UI

If cert_required is false, then ca_certs will not really matter.
Fail early if certificate files are missing
Merge pull request #94 from vuntz/ssl-fixes

https://github.com/crowbar/barclamp-keystone/pull/94

Merged by devtool for cloudsleuth
Provide keystone protocol to keystone.conf, used in v3 endpoints
Allocate public IP address to keystone-server nodes

The keystone server needs to be accessible from the external network, so
that OpenStack command line tools work.
Merge pull request #99 from vuntz/allocate-public-ip

Allocate public IP address to keystone-server nodes
Merge pull request #96 from saschpe/release/pebbles/master

Provide keystone protocol to keystone.conf, used in v3 endpoints