Add search functionality for lesson plans and wrote model, controller, and feature specs
Add missing file
Search handles nil case

Remove search template and render index instead
Search returns all lesson plans when blank or nil
Merge branch 'search' of https://github.com/luketower/yo_teach into luketower-search

Conflicts:
  app/models/lesson_plan.rb
  spec/features/lesson_plans_spec.rb
Merge branch 'master' into luketower-search