move user preferences to core module

src/app/app.component.ts

src/app/app.module.ts

src/app/core/actions.ts

src/app/core/core.module.ts

src/app/core/effects.ts

src/app/core/reducer.ts

src/app/dars/dars.module.ts

src/app/dars/store/effects.ts

src/app/degree-planner/degree-planner.module.ts

src/app/degree-planner/store/effects/plan.effects.ts

src/app/degree-planner/store/reducer.ts

src/app/degree-planner/store/selectors.ts