added blank files for course, enrollment, and student classes
created structs for student and courses
created class to import csv files
changed structs to classes
create ActiveCourses class to encapsulate course data
move csv iteration up into csvimporter
add attr_accessor for student model
fixed call to each file line from a method name to a key call
begin formatting courses for output
create call method on Fromat Courses to format output of active classes and active students
change name of ActiveCourses to school to better reflect class use.  Change methods under School to set_* instead of add_* to reflect that methods do not only add but set objects if they already exist
move csv importer into a new file under models
renamed csv_parser into school.rb