feat: change default crop behaviour to undefined from faces

[frederickfogerty]

BREAKING CHANGE: default crop behaviour is now imgix default, not faces

Description

This PR removes the default setting for crop. The old behaviour may be confusing to new developers, so it is better for them to enable it if they would like the behaviour.

This PR fixes #34

New Feature

• [N/A] If this is a big feature with breaking changes, consider [opening an issue][issues] to discuss first. This is completely up to you, but please keep in mind that your PR might not be accepted.
• [x] Run unit tests to ensure all existing tests are still passing
• [x] Add new passing unit tests to cover the code introduced by your PR
• [x] Update the readme
• [x] Add some steps so we can test your cool new feature!
• [x] The PR title is in the conventional commit format: e.g. feat(<area>): added new way to do this cool thing #issue-number
• [x] Add your info to the contributors array in package.json!

Steps to Test

Review the changes to the tests.

[Duder-onomy]

Going to merge this! Your crushing it.

[frederickfogerty]