Set proper capabilities for Courier Notice post type

[maxinacube]

Proper capabilities need to be set for the Courier Notice post type.

In order to make a Gutenberg block for Courier, we need the post type registration to set show_in_rest as TRUE.

[maxinacube]

To go along with this, we need to see if we can limit Courier Notices to only use the Classic Editor

https://gist.github.com/uptimizt/b99ef36aabab1ff641414e593e73d040
For anybody arriving here via a web search, the filter name in WordPress 5.0 is use_block_editor_for_post_type instead of gutenberg_can_edit_post_type.
Everything here --WordPress/gutenberg#7595
add_filter( 'use_block_editor_for_post_type', '__return_false' );

[aaronware]

I can take care of this one.