Update "Current Commissioners" in a grid to account for three person vacancy

[dorothyyeager]

Summary

What we're after:
We want the "Current commissioners in a grid" to put the three active Commissioners first, followed by the three vacancies. When we updated for Commissioner Petersen's departure, this was the result:

Related issues

List any relevant related issue(s)

• [Due 9/3/19] Update Wagtail pages to reflect commissioner departure #3128
• [Due 9/3/19] Update Homepage to reflect commissioner departure #3129

Completion criteria

List action items that need to be done to complete this task. List in checklist formatting.

• Reconfigure the grid of Commissioners to put all active ones first
• Change "vacant Vice Chair seat" to "vacant seat"
• Doublecheck https://www.fec.gov/about/leadership-and-structure/ to make sure it turned out this way.

[dorothyyeager]

Resolved by hotfix at #3131 so closing.