[HOTFIX - USE GITFLOW] Update commissioner listing on homepage and leadership landing page

[patphongs]

Summary

• Resolves [Due 9/3/19] Update Homepage to reflect commissioner departure #3129
  Removes departing commissioner from homepage as reflected in the ticket.

Impacted areas of the application

List general components of the application that this PR will affect:

• Homepage

Screenshots

How to test

• Checkout branch
• ./manage.py runserver
• Ensure that the HTML on the homepage reflects the commissioner change accurately. http://localhost:8000/
• Go to the leadership and structure page here: http://localhost:8000/about/leadership-and-structure/
• Ensure that if a Chair and Vice Chair are populated that it will put those first. Otherwise show commissioners in alpha by last name

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[codecov-io]

Codecov Report

Merging #3131 into master will decrease coverage by 0.07%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #3131      +/-   ##
==========================================
- Coverage   74.76%   74.69%   -0.08%     
==========================================
  Files         119      119              
  Lines        7158     7165       +7     
  Branches      633      633              
==========================================
  Hits         5352     5352              
- Misses       1806     1813       +7

Impacted Files	Coverage Δ
fec/home/templatetags/commissioners.py	33.33% <0%> (-21.22%)	⬇️

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[rfultz]

Looks good. Do we need to do anything about his page? /about/leadership-and-structure/mathew-s-petersen/ (Also, his page's slug is misspelled.)

[patphongs]

oh good point @rfultz, we can put in a wagtail redirect for the misspelled slug and update the page name. I'll document that in this ticket #3128, which the content team will take care of on 9/3.