support for mapping tags to name.default aliases

[missinglink]

this PR allows OSM tags to be mapped as aliases of the name.default field.

the schema/name_osm.js file contains a mapping of OSM tags to name.* fields.

prior to this PR we were only able to map 1:1 from OSM to the Pelias model.

this PR now supports multiple values in that object set as default, in this case the additional tags will be mapped as aliases of the name.default field.

the configuration also adds an additional inenumerable property called _primary which defines which of those is considered the 'primary' name.

an example tag mapping:

osm_tags = { name: "foo", short_name: "bar", reg_name: "baz" }

# prior to the PR
name = {
  default: "foo",
  short: "bar",
  regional: "baz"
}

# after the PR
name = {
  default: [ "foo", "bar" ],
  regional: "baz"
}

---

I enabled 3 tags as aliases of default: [ short_name, alt_name, loc_name ], of these only short_name is supported by nominatim.

https://wiki.openstreetmap.org/wiki/Names#Key_Variations

The test/fixtures/combined_vancouver_queens.json file in this PR includes a diff which shows and example of the expected changes.

[orangejulius]

The most recent Nextzen full planet build includes these changes, but I haven't looked at the results yet. I'm spinning up a cluster to do that now.