user can create course
Backfill User#full_name spec
Course#instructor_last_name

- Adds spec for Course.belongs_to(:teacher)
Refactor courses view: law of demeter violation

- Prefer Course#instructor_last_name over #teacher.last_name
- Render courses via partial instead of using @courses.each
User can edit course

Refactored course edit, new views to use _form partial
fixed typo
Teacher (User) can add assignments

- Update new/edit links to standardized I18n format
- Update submit buttons to standardized I18n format
Update layout links to I18n
Update date attributes on Assignment
refactor form date selection
refactor form text field submission
refactor dropdown select
Refactor, abstract prefix
Refactor, add FormCompletionHelper
Refactor, allow singular and plural method calls
Refactor, abstract form submit
Clean up assignment views