Begin author authentication build using Sorcery gem.

 * Add 'sorcery' to gemfile
 * bundle
 * rails generate sorcery:install --model=Author
 * rails generate scaffold_controller Author username:string
   email:string password:password password_confirmation:password
 * change authors/_form.html.erb to .haml
  - remove erb form and replace with simple-form syntax.
Revised view files for new Login system.

 * Changed 'new' and 'show' views/authors view files to .haml and made
  all required edits to implement simple-form.
 * Remove fields in index.html.erb which show password and
  password_confirmation fields.
 * Add code to show whether user is logged in or not in
  views/authors/index.html.erb file.
Create routes for 'authors' in config/routes.rb
In Authors model, confirm that 'password' and 'password_confirmation'
entries are identical.
Add AuthorSessions controller.

 * Now we have the necessary actions to log in or log out of the
 application.
Add (1) Create Author and (2) User Login/out
Login page is only accessible page to non logged in users
Add link to "Create Account" on Login page.

 * Also removed application layout link "Log Yo'self In!" which appeared
  every page. Since only logged in users can access the app, there is no
  need for this link.