Replace coords array property with lat, lon.

lib/(address, addresses/(openaddresses, osm, tiger)).js
	-Flatten the `Address.coords` array to `lat` and `lon`
	properties.
	-Modify dataset-importer `Address()` calls accordingly.
Merge branch 'refactor/flatten_coords' into develop

lib/address.js
	-Flatten the `Array.coords` array into `lat`/`lon` properties.
Fix failing tests by updating to reflect d005a78.

test/(openaddresses, osm, tiger).js
	-Fix failing unit-tests by updating them to reflect the changes
	introduced by d005a78.
Add country property to Address objects.

lib/address.js
	-Add `country` argument to `Address()` constructor.
	-Assign it as a new property of `Address` objects.

lib/addresses/*.js
	-Update `Address()` calls accordingly.
Update tests to reflect new Address country prop.

test/(openaddresses, osm, tiger).js
	-Update broken tests to reflect the new `Address.country`
	property, added in 82e497c.
Merge branch 'feature/country_prop' into develop

lib/(address.js, addresses/*)
	-Introduce an `Address.country` property.
Change most Address property names.

lib/address.js
	-Change most `Address` property names to conform to the
	address-deduper's schema.
Fix breaking tests; update them against 39e5dcb.

test/(openaddresses, osm, tiger).js
	-Fix failing unit-tests by updating them to reflect the
	`Address` property name-changes introduced in 39e5dcb.
Merge branch 'feature/rename_address_props' into develop

lib/address.js
	-Rename most `Address` properties to conform to the schema
	required by the address-deduplicator
	(https://github.com/openvenues/address_normalizer/blob/master/
		address_normalizer/models/address.py).
Add a deduplicate stream module.

lib/deduplicate_stream.js
	-Add a module that exposes a stream to deduplicate addresses
	coming down the pipeline.
	-Currently a little rough around the edges: undocumented,
	lightly tested, etc.
Refactor the deduplicate_stream module.

lib/deduplicate_stream.js
	-Restructure the `deduplicate_stream` module, abstracting chunks
	of functionality into functions (eg, `sendBatch()`,
	`bufferBatch()`).
Thoroughly document the duplicates_stream module.

lib/deduplicate_stream.js
	-Add documentation to the module header, all functions, and
	tricky code.
Convert from through to through2.

lib/(addresses/(openaddresses, osm, tiger), dataset_import).js
	-Convert from the `through` module to the more up-to-date
	`through2`, which uses the streams2 API.
Rate limit deduplicate_stream.

lib/deduplicate_stream.js
	-Implement rate-limiting in the stream exported by the
	`deduplicate_stream` module, to prevent it from throttling the
	slower deduper.
Document the deduplicate_stream's rate-limiting.

lib/deduplicate_stream.js
	-Add an argument `maxLiveRequests` to
	`createDeduplicateStream()`, which allows the caller to
	configure the stream's rate-limiting.
	-Add documentation regarding rate-limiting.
Update package.json dependencies.

package.json
	-Add the dependencies required by the features added in this
	branch.
Merge branch 'feature/rename_address_props' into develop

lib/address.js
	-Rename most `Address` properties to conform to the schema
	required by the address-deduplicator
	(https://github.com/openvenues/address_normalizer/blob/master/
		address_normalizer/models/address.py).
Merge branch 'feature/deduplicate' into develop

lib/deduplicate_stream.js
	-Add a module that interfaces with the pipeline's external
	address deduper to deduplicate a stream of addresses.
Convert unit-tests from through to through2.

test/(openaddresses, osm, tiger).js
	-Unit-tests weren't converted from the `through` module to
	`through2`, which was adopted throughout the project in 92b1833.
	-Should fix failing CI tests.
Merge branch 'develop'

lib/(deduplicate_stream, address).js
	-Integrate the pipeline's external address-deduplicator by
	introducing a `deduplicate_stream` module that interfaces with
	it.
	-Change the `Address` schema to accommodate the format expected
	by the de-duplicator.