Chore: Update rubocop config
Tests: Add a secure setting to the standard setting fixture YAML

--------------------------------------------------------------------------------
Change-Id:     I49e2ecb166114af89eebeb18e9af3acf6baccbf5
Signed-off-by: Jeff Felchner <accounts+git@thekompanee.com>
Feature: Add --only-secure option to 'show'

This option allows 'show' to filter the settings that it shows to only those
which are secured/securable.

Closes #32

--------------------------------------------------------------------------------
Change-Id:     I6c9eeb7027dd5c18bbf8ee4826399942a80546c8
Signed-off-by: Jeff Felchner <accounts+git@thekompanee.com>