Set up statistics collection in Wagtail; upload Press replacement doc and put in www redirect

[dorothyyeager]

Summary

What we are after:
We migrated press statistical summaries to fec.gov and the related PDFs to the S3 bucket. Press has a PDF to replace one of those PDF files. That means we need to do a few things.

Related issues

• Move statistical data summaries from transition S3 to production S3 #4052 - migration of statistics to S3 bucket

Completion criteria

• Collection in Wagtail created for Press summaries - *This is only needed this one time unless Press wants more collections.
• New replacement files uploaded to Wagtail
• Update link on the related page (hard-coded)
  - [ ] www redirect put in place for the file that's in S3 to be replaced.

~### Future work

• We will need to test that redirect along with others after the 13.11 release is deployed.~

[dorothyyeager]

@patphongs noted that we will upload the ones for 2020 to the S3 bucket and she took care of this here and uploaded the replacement files for the ones in this ticket (18 month IE). For the next few for 2020, we'll add the 2020 21- and 24-month to the content-S3 bucket.

For 2022, we'll figure out how to upload via Wagtail and update links in #4296