migrate isbn for issue 48
change readme to reflect issue 48
validate isbn lengths
make isbn's strings
added isbn10 and isbn13 views & validations

passing all tests, 100% simplecov.
Merge branch 'master' into isbn

Conflicts:
	db/schema.rb
Merge pull request #52 from nbirnel/isbn

Isbn
removed welcome controller, added a root route to books
Merge pull request #55 from Mattsface/routing_changes

removed welcome controller, added a root route to books
Merge branch 'master' into authors

Conflicts:
	config/routes.rb
	db/schema.rb