Fixes "Captain America" and "Albert Einstein" typos.

Seems to also remove trashed items.

Fixes #23, #27
Moves "Menu Description" custom menu item under "Advanced" menu

Fixes #9
Remove inline styles being added to the data.

Fixes #12
Beefs up `composer.json` file.
Cleans up `.gitignore`.
Removes `changelog.md`.
Renames license file.
Gives the README a serious makeover.
Cleans up the comments on the WP-CLI script.
Adds `CONTRIBUTING.md` file.

Fixes #36
Moves logo screenshot into the `screenshots` folder.
Readds a simplified changelog.
Bumps version for 1.5.0 release.