add fee column to payments
Merge pull request #29 from epicodus/add_fee_column

add fee column to payments
add total_amount to plan
set recurring_active to false when user is paid up
keep processing fee seperate from the principal amount
refactor payments controller
ensure user does not pay more than what is owed
refactor calculate_fee method
Merge pull request #31 from epicodus/stop_recurring

Stop recurring payments
add assessment model, routes, controller, and specs
add validations to assessment model
add assessment requirement model, update associations
rename assessment_requirement model to requirement -- cherry picked
display submissions
merge grades
add association between user and grade
adjust relationships surrounding assessments

Before grades served as a join between an assessment and a requirement
to give a score for the one requirement on a submission. This groups
grades together into a review, allowing us to have a note that isn't
tied to a specific grade, as well as a user who did the reviewing.
create index view for assessments
remove authorization from submission controller
allow user to view and submit an assessment