Wide gutenberg settings support

[ashleykolodziej]

Changes proposed in this pull request

• Adds support for wide and full widths in Gutenberg.

Required pull requests to merge (usually a pull request on Foundation or a plugin)

None.

Test sites

Clone these sites to your sandbox, and review them briefly. Does everything work as expected?

• ID Demos - BU Programs http://id-demos.cms-devl.bu.edu/bu-programs/degree-program/sample-program-page/
• ID Demos - BU Blocks http://id-demos.cms-devl.bu.edu/bu-blocks/
• ID Demos - BU PrePress http://id-demos.cms-devl.bu.edu/bu-prepress/
• One Editorial tk
• BULB tk

Note: these changes will not affect Questrom as it is a 1x theme.

Review checklist

• I have tested my changes in my sandbox on Responsive Framework and at least one child theme.
• I have tested any new filters or action hooks I have introduced in a child theme to ensure they work correctly.
• I've reviewed the contribution guidelines.
• I've updated CHANGELOG.MD with a brief explanation of the changes in this pull request in the unreleased section.
• My code follows BU Coding Standards.