Merge branch 'release-v2.1.11' into develop
Standardize wording on "invalid field" error messaging
Add puppet flag files to .gitignore
Remove api_key authentication check for items_context and collections_context
Refactor results cache key into its own module with tests
Add .bundle/config to .gitignore
Version v2.1.12
Merge branch 'release-v2.1.12'