Enhance product view

* fix the layout so it has the analyzer navbar on the left
* switch the form to use .as_p() which makes it a tiny bit easier to use
* tweak the view code so that it makes it easier to update existing
  products
* add some "helpful" directions so it's a little clearer as to what's
  going on
Merge pull request #335 from willkg/enhance-products-view

Enhance product view
Add PII-related notes to the API fields
[bug 799562] Clarify API field documentation

* adds max lengths where appropriate
* adds note about including PII-related informational text for
  description and email fields
* adds max_length items to manufacturer and device fields in the
  serializer
[bug 1055789] Restrict front page dashboard and api to 6 months
Merge pull request #336 from willkg/1055789-restrict-dashboard

[bug 1055789] Restrict front page dashboard and api to 6 months