Lesson Plan search and filter

- Changed dropdown to submit page request
- Added sorting on individual classes
- Added searching on individual classes
Search bug

- Fixed js to trigger on dropdown change only
- Moved lesson plans index param checking to controller boundary
Gemfile update

- Updated rspec to avoid minitest warning
- Upgraded gems
Sortable update

- Added params[:search] to link if it exists
- Updated specs
Fix search to eliminate case dependence
Merge branch 'master' of github.com:luketower/yo_teach