feat: Add the concept of a 'label builder'

This allows us to control higher level aspects of the label, such as
whether or not administrative data comes first.

Most parts of the world would write an address with the
housenumber/street first, and admin info second, but not _all_ places do
this.

With a label builder we can support these places

labelGenerator.js

@@ -144,19 +144,30 @@ function buildPostfixLabelParts(schema, record) {
   return [record.name.default];
 }
 
-module.exports = function( record ){
-  const schema = getSchema(record.country_a);
-  const separator = _.get(schema, ['meta','separator'], ', ');
+// builds a complete label by combining several components
+// the parts generally follow this format
+// prefix parts: the venue name or address
+// admin parts: administrative information like city
+// postfix part: higher level admin areas
+function defaultBuilder(schema, record) {
 
   // in virtually all cases, this will be the `name` field
   const prefixParts = buildPrefixLabelParts(schema, record);
   const adminParts = buildAdminLabelPart(schema, record);
   const postfixParts = buildPostfixLabelParts(schema, record);
 
-  let labelParts = _.concat(prefixParts, adminParts, postfixParts);
+  const labelParts = _.concat(prefixParts, adminParts, postfixParts);
 
   // retain only things that are truthy
-  labelParts = _.compact(labelParts);
+  return _.compact(labelParts);
+}
+
+module.exports = function( record ){
+  const schema = getSchema(record.country_a);
+  const separator = _.get(schema, ['meta','separator'], ', ');
+  const builder = _.get(schema, ['meta', 'builder'], defaultBuilder);
+
+  let labelParts = builder(schema, record);
 
   // third, dedupe and join with a comma and return
   if (isInKOR(record)) {