Turn params into defaults and formalize it

The `params` vs. `bind` class distinction has been blurry for a long time. I'm
formalizing it.

`params` is now `defaults` and its purpose is to gather platform-specific
variation into a single scope. These variables are related to situating a BIND
server on a particular platform and it should not ever be necessary or perhaps
even possible to change them as a matter of preference. Rather, correct values
are function of e.g. `$osfamily` or `$operatingsystem`.

The parameters of the `bind` class are limited to those that control the
server's feature set. These parameters *are* matters of preference and/or
purpose, rather than platform.

Also, I have taken some care to develop a convention for direct references to
qualified parameters where they are re-scoped into the local scope centrally at
the top first, and subsequent references are to the local value. This should
minimize future code churn and also aid readability.

data/osfamily/Debian.yaml

@@ -1,13 +1,12 @@
 ---
-bind::params::supported: true
-bind::params::bind_user: 'bind'
-bind::params::bind_group: 'bind'
-bind::params::bind_package: 'bind9'
-bind::params::bind_service: 'bind9'
-bind::params::nsupdate_package: 'dnsutils'
-bind::params::confdir: '/etc/bind'
-bind::namedconf: '/etc/bind/named.conf'
-bind::cachedir: '/var/cache/bind'
-bind::rndc: true
+bind::defaults::supported: true
+bind::defaults::bind_user: 'bind'
+bind::defaults::bind_group: 'bind'
+bind::defaults::bind_package: 'bind9'
+bind::defaults::bind_service: 'bind9'
+bind::defaults::nsupdate_package: 'dnsutils'
+bind::defaults::confdir: '/etc/bind'
+bind::defaults::namedconf: '/etc/bind/named.conf'
+bind::defaults::cachedir: '/var/cache/bind'
 
 bind::updater::keydir: '/etc/bind/keys'

data/osfamily/RedHat.yaml

@@ -1,14 +1,13 @@
 ---
-bind::params::supported: true
-bind::params::bind_user: 'named'
-bind::params::bind_group: 'named'
-bind::params::bind_package: 'bind'
-bind::params::bind_service: 'named'
-bind::params::nsupdate_package: 'bind-utils'
-bind::params::managed_keys_directory: '/var/named/dynamic'
-bind::params::confdir: '/etc/named'
-bind::namedconf: '/etc/named.conf'
-bind::cachedir: '/var/named'
-bind::rndc: true
+bind::defaults::supported: true
+bind::defaults::bind_user: 'named'
+bind::defaults::bind_group: 'named'
+bind::defaults::bind_package: 'bind'
+bind::defaults::bind_service: 'named'
+bind::defaults::nsupdate_package: 'bind-utils'
+bind::defaults::managed_keys_directory: '/var/named/dynamic'
+bind::defaults::confdir: '/etc/named'
+bind::defaults::namedconf: '/etc/named.conf'
+bind::defaults::cachedir: '/var/named'
 
 bind::updater::keydir: '/etc/named/keys'