Chore/festival backporting

[noahsettersten]

This rolls up a number of changes for recent issues discovered during the Festival Giving build-out, including:

• Adds devise_invitable
• Adds new Address model with polymorphic association
• Sets up CircleCI 2.0 and CodeClimate
• Adds shared example for basic testing of Administrate dashboards
• Installs the foundation-specific views for Kaminari
• Fixes seeding when User model has paranoia enabled
• Adds Home link to bottom of Administrate sidebar
• Fixes admin link by disabling turbolinks

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