Added Pry, updated links to point to Rails on Maui

* Updated README.md
Created user/finder_methods concern

All tests pass.
Moved tests to own file for User::FinderMethods concern
Create User::FeedMethods concern
Add Draper Gem
Generate Draper decorator file for User model

Ran command:
  rails generate decorator User
Convert partial to use parameters rather than instance variable.

Partial takes parameter user.
Add launchy gem for debugging specs

Call save_and_open_page to open html in browser to debug specs.
Added user_decorator.rb

* Displays number of followers with formatted number
* Added (slow) test
Improved test speed by consolidating 2 slow tests.

Rather than create the 1000 users twice...Do it once.
Disable super slow spec UserDecorator spec

* Too slow because it creates 1000 users.
* Marking with xit.
Add app/presenters directory to default load path
Add caching to following/followers pages

1. Changes to the relationship model touch both the follower and
   followed user.
2. Changed the calculation of the counts of the followers and
   followed_users to use 'size' rather than 'count', which would always
   run a 'count' query, when we might be fetching the total anyway.
3. production.rb changed to debug logging to show all queries and cache
   lookups.
4. UsersController got added instance variable @subtitle to cause an
   extra query.
Added Users::FollowPresenter

* Values are memoized so that queries are only done when value is needed
  for display. This helps avoid unnecessary running of queries.
* Try out application running as
  rails s -e production
* Observe queries first time and second time.
* Notice that before abstracting out the presenter, the count query in
  the controller ran even if the view was cached.
Move cache key to presenter