Submit errors are not removed on `fields.remove` call

[trefnis]

Are you submitting a bug report or a feature request?

A bug.

What is the current behavior?

What is the expected behavior?

Submit error is matched with array field - when the field is removed, submit error is also removed

What's your environment?

Forked from offical example:

"dependencies": {
    "styled-components": "2.2.4",
    "react-final-form-arrays": "1.0.0",
    "react-final-form": "1.1.1",
    "react-dom": "16.2.0",
    "react": "16.2.0",
    "final-form-arrays": "1.0.0",
    "final-form": "1.2.1"
  }

Locally:

    "final-form": "^4.1.0",
    "final-form-arrays": "^1.0.4",
    ...
    "react-final-form": "^3.0.5",
    "react-final-form-arrays": "^1.0.3",

[vitalii-parkhomenko-official]

It seems fixed, waiting for review.
#48