Display classes on student edit page for adding classes.

* app/assets/javascripts/students.js.coffee: Initialize studio
  calendar in a function so same code can be used to initilize all
  studio calendars.

* app/models/course.rb: Add a studio filter

* app/models/parser.rb: Update to handle classes on Saturday morning

* app/views/courses/index.json.jbuilder: Construct JSON using jbuilder
  which is packaged in rails 4.1

* app/views/students/_form.html.erb: Display all studio class
  calendars.

* db/schema.rb: Updates to schema.

* spec/models/parser_spec.rb: Add tests for handling Saturday morning
  and afternoon class times correctly.
Add teacher model

* Teacher has many courses
* A company has many teachers
* Add duration method to determine length of a course in hours for
  payroll