Install devise gem.  Generate devise views (/devise folder full of new views).  (To Do Next: Need to generate model that will be used by Devise, in our case User).
use Devise generator to create User model.
Clean up some Devise templates using Bootstrap classes.
Update database.yml file, to reflect that the production db is postgres (hopefully fixing my heroku error that only occured once I attempted to upload photo).
attempt to fix dropbox. set new key
Comment @listings var to determine error.
revert
more testing to get app to work on Heroku.
Correct production.rb file to point to app (NOT localhost:3000, which is only for development.rb) Revert previous testing line.
In Gemfile, mMve pg out of production only.
include 'http://' at beginning of host in production.rb.
stuff
manually revert by commenting out and deleting lines to get to working version.  Note, less secure.
Working, but unsecure -- Move dropbox.yml app_secret and access_token_secret into another file (as a constant)  which is gitignored.  Also, all attached files are being accessed by Dropbox (both local and production) -- when one is erased locally, it causes an error in production (dropbox is searching for a missing image).  Make dropbox only work for production by giving access selectively (in listing.rb).
Move dropbox.yml app_secret and access_token_secret into a gitignore file.
Not working (found problem) ((now using figaro gem ch6,pt2) Need to TELL HEROKU where to find secret key (instructions at bottom of figaro gem github page).
Working!  Needed to run 'figaro heroku:set -e production' to tell heroku where to find the 'secret' values in the ENV[] hash.  (NOTE: The tutorial says to run
'rake figaro:heroku' but that seems to be deprecated.