Adding custom admin panels for news and updates

[noahmanger]

This uses Wagtail's ModelAdmin hooks to implement custom admin panels for the latest updates.

Now, there will be a new menu item for "News and updates", which contains links to each type of update:

Each one of those takes you to a view that is default sorted by the original date of the item:

I think this is actually a much better approach than the "Folder" concept earlier as it doesn't require any redirects or moving pages around.

[codecov-io]

Codecov Report

Merging #1200 into release/public-20170811 will increase coverage by 1.05%.
The diff coverage is 94.44%.

@@                    Coverage Diff                     @@
##           release/public-20170811   #1200      +/-   ##
==========================================================
+ Coverage                    64.15%   65.2%   +1.05%     
==========================================================
  Files                          186     186              
  Lines                         5325    5541     +216     
  Branches                       404     409       +5     
==========================================================
+ Hits                          3416    3613     +197     
- Misses                        1881    1899      +18     
- Partials                        28      29       +1

Impacted Files	Coverage Δ
fec/home/wagtail_hooks.py	95.55% <94.44%> (+6.08%)	⬆️
fec/home/models.py	87.29% <0%> (+1.42%)	⬆️

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[ccostino]

This is awesome, @noahmanger, thank you!

I noticed one thing with the menu though, and I think it's just extraneous ModelAdmin registration statements that aren't needed. I wanted to check and see if you experience the same behavior or not to verify whether the adjustment I recommended is needed.

[ccostino]

It looks like these are extra register statements that aren't needed... you only need the last one for the menu itself to show up with the sub items in it. What I found was that with these statements in place, you see them in the main menu too:

Where as if you just keep the one below, they go away and you have just the one menu item. :-)

[noahmanger]

Good catch! I made that fix earlier but apparently forgot to push it. There it is.

[ccostino]

Awesome, we're good to go! :-)

[dorothyyeager]

Thank you @ccostino @noahmanger