Refactored PlanType to FeePlan.
Added event, amount, pay_type(labeled as type in rails admin) to fee_plans table. Added custom validations for them.

== Rails admin note on pay_type ==

Actually I tried with type column at first and spend some time figuring why it's not working. Turned out that name can't be type, so I renamed it to pay_type. I'm really waiting for feedback on this one.