Parserator challenge

[NoahAppelbaum]

Overview

This PR consists of two major parts:

• A backend JSON API endpoint, which parses U.S. address strings using usaddress
• JavaScript for the previously built static frontend, which provides a simple form for a user to enter an address, calls the API, and renders the returned parsed address information in the UI

This PR also includes tests for the API endpoint, and a few other small fixes and adjustments (enumerated below)

Closes #XXX

Demo

Functioning app with network request:

Displaying an error message:

Tests passing

Notes

Other changes:

• Added npm to the apt-get... line in the Dockerfile, to fix an npm not found error when building
• In the Index.html template, changed the inline display: none styling on the address results div to use Bootstrap's d-none utility class. This maintains consistency with the rest of the page's styling, and makes manipulating the div's styling through JavaScript more straightforward.
• This coding challenge was completed by me, Noah Appelbaum

Testing Instructions

How to Test

• Build with

  docker-compose build
  

• Run tests with

  docker-compose -f docker-compose.yml -f tests/docker-compose.yml run --rm app
  

New Test Cases

• test_api_parse_succeeds -- The API should respond successfully, with expected JSON, on a valid address
• test_api_parse_succeeds_on_empty_string -- the API should respond successfully on an empty string, consistent with the output of usaddress and expected frontend behavior
• test_api_parse_raises_error -- The API should raise an error on an invalid address input
• test_api_parse_raises_error_on_missing_address_string -- The API should raise an error when missing address input (from a malformed request, e.g.)