Add isbn_validation gem to handle isbn validations better
Only display books with a seller

- don't display duplicate books
Saying that a user wants to sell a book adds that book to the "to sell"
list for that user
Add desired books to "To Buy" section of book index
WIP: Working on seller finder
Full implementation of matching - maybe?

- update seed file
- going to test against a scenario
Finalize matching code

- don't show completed matches (different from scheduled)
- fix variable name for flash messages
Merge branch 'master' into matching-logic

- updates seeds file to have real books

Conflicts:
	app/controllers/matches_controller.rb
	app/models/user.rb
	db/schema.rb
	db/seeds.rb
Remove to buy section of the book index which doesn't make sense
Merge pull request #10 from dleve123/matching-logic

Matching logic