Scaffold out basic transactions model and UI (#478)

* Transaction scaffold

* Rough in transaction views

* Fix sort order

* Fix mass assignment issue

* Fix test

* Simplify CI workflow

* Don't seed db before test

app/models/account.rb

@@ -3,6 +3,7 @@ class Account < ApplicationRecord
   belongs_to :family
   has_many :balances, class_name: "AccountBalance"
   has_many :valuations
+  has_many :transactions
 
   delegated_type :accountable, types: Accountable::TYPES, dependent: :destroy