Remove enzyme and react-addons-test-utils

[cherewaty]

Purpose

yarn install gave warnings about unmet peer dependencies for enzyme and react-addons-test-utils. The enzyme version specified didn't work with React 16, and react-addons-test-utils is deprecated as of React 16.

The only test using enzyme in this repo was routes.js.disabled, which appears to have been disabled since March 2017: f803bc3#diff-9c45fa6561a34e0c866002ae185407f0

Approach

Remove enzyme, react-addons-test-utils, and routes.js.disabled test.

stripes-connect is the only other folio-org repo using enzyme, and it defines its own dependency on it.

[cherewaty]

bump @skomorokh

[skomorokh]

Ya, doesn't seem like those defunct tests are going to be resurrected nor will future tests use that approach.

Does anything else use mock-require?

[cherewaty]

Nothing else in folio-org was using mock-require, so I removed that too.