adds test suite extension shoulda-matchers

updates Gemfile and Gemfile.lock
adds example for has_secure_password to user_spec

uses shoulda-matchers

fixes #42
Merge branch 'Imnudar-add-shoulda'
updates bcrypt-ruby

bumps version latest, updates Gemfile and Gemfile.lock

fixes #45
Merge branch 'Imnudar-update-gem/bcrypt-ruby'