Add tls support

- Add the missing bootstrap_expect param
- Add the missing encrypt param
- Add encrypt_enabled param to make Consul gossip encryption explicit
We should be using [derived attributes](https://coderanger.net/derived-attributes/) and evaluating them lazily in the appropriate recipe(s). The example here would be as follows:
```ruby
default['consul']['config_dir'] = '/etc/consul.d'

default['consul']['ca_path'] = "%{config_path}/ca.pem"
default['consul']['cert_path'] = "%{config_path}/cert.pem"
```

And inside of the Chef recipe itself you would interpolate the string:
```ruby
ca_cert_path = node['consul']['ca_cert'] % { config_path: node['consul']['config_path'] }
cert_path = node['consul']['cert_path'] % { config_path: node['consul']['config_path'] }
```