Implement a helper script for zone reloads

It turns out the `rndc` command that was intended to reload a managed zone
wasn't working (see PR #91 for reference) if more than one view included the
zone. The helper script is really just a wrapper around the `rndc` command
itself, it translates its final parameter into a domain/class/view tuple and
pass the leading parameters and the tuple to `rndc`.

templates/rndc-helper.erb

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+CONFDIR=<%= @confdir %>
+
+function param_lookup() {
+  local zone_name="${1}"
+  local domain="$(grep "^${zone_name}:" ${CONFDIR}/domain-mappings.txt | cut -f2 -d:)"
+  grep "^${zone_name}:" ${CONFDIR}/view-mappings.txt | cut -f2 -d: | sed -e "s/\(.*\)/${domain} IN \1/"
+}
+
+zone_name="${!#}"
+
+param_lookup "${zone_name}" | while read Z; do
+  if [ $# == 1 ]; then
+    echo $Z
+  else
+    sudo rndc "${@:1:$(($# - 1))}" $Z
+  fi
+done

templates/view-mappings.erb

@@ -0,0 +1,3 @@
+<%- @zones.each do |zone| -%>
+<%= zone %>:<%= @name %>
+<%- end -%>