Add 'no-unused-vars' eslint rule, remove unused variables

.eslintrc

npm-shrinkwrap.json

package.json

...ent/app/admin/metadata/components/MetadataEditor.react.js

...ient/app/admin/metadata/components/MetadataField.react.js

...ent/app/admin/metadata/components/MetadataSchema.react.js

...ient/app/admin/metadata/components/MetadataTable.react.js

...ces/frontend_client/app/admin/metadata/metadata.module.js

...es/frontend_client/app/admin/people/people.controllers.js

resources/frontend_client/app/auth/auth.controllers.js

resources/frontend_client/app/card/card.charting.js

resources/frontend_client/app/card/card.controllers.js

resources/frontend_client/app/card/card.directives.js

...ntend_client/app/components/CreateDashboardModal.react.js

...ontend_client/app/components/DeleteQuestionModal.react.js

...end_client/app/components/LoadingAndErrorWrapper.react.js

...rontend_client/app/components/QuestionSavedModal.react.js

...urces/frontend_client/app/components/RadioSelect.react.js

...frontend_client/app/components/SaveQuestionModal.react.js

.../frontend_client/app/components/SortableItemList.react.js