Store similar courses in database

[kevinhu]

• Add one of the course embedding algorithms to the import pipeline
• Store linked courses: perhaps a junction table?
  

  ferry/ferry/database/models.py

  Lines 40 to 51 in 3399f14

  	# Course-Professor association/junction table.
  	course_professors = Table(
  	"course_professors",
  	Base.metadata,
  	Column("course_id", ForeignKey("courses.course_id"), primary_key=True, index=True),
  	Column(
  	"professor_id",
  	ForeignKey("professors.professor_id"),
  	primary_key=True,
  	index=True,
  	),
  	)