Modify mailer default url to use just the hostname

- Modify mailer default url to use just the hostname
  derived from APP_CONFIG[:site_url]
Handle confirmation token is invalid error

- Handle confirmation token is invalid error.
Fix unable to logout when on security questions.

- Edit path options within session_sensitive_path.
Add help to the list of session_sensitive_path.
Add pepper setup to setup.rb

- Generate peppers when first setting up
  the settings.yml file.

- Generate pepper if not existing in the
  settings.yml file in subsequent updates.
Delete tasks related to site_keys.rb

- Delete tasks related to site_keys.rb as
  it is no longer being used.

- Refer to Scott's comment on Github
  https://github.com/concord-consortium/rigse/pull/26#issuecomment-15240475
Update core-extensions documentation

- Add note about moving the Hash module patch
  into lib/app_settings.rb
Update README with Devise changes

- Remove references to Restful Auth and
  config/initializers/site_keys.rb

- Replace section of Restful Auth with
  Devise info.

- Add info about pepper to Devise section.
Update README with Devise changes

- Update reference to RESTful Authentication
  in the User Roles section referring to Bort.
Update spec test fixtures and initialization.

- Modify controller_helper.rb to update APP_CONFIG[:pepper]
  instead of REST_AUTH_SITE_KEY for test users.

- Modify user fixtures with updated password salts and
  encrypted passwords to use with test pepper.
Update spec test initialization.

- Modify controller_helper.rb to update Devise config
  with test value of APP_CONFIG[:pepper].
Merge updates from previous pull request branch

- Merge branch 'pull_request_03_12_2013_a'
  into test_cleanup_03_20_2013_a.