Net worth calculation (#508)

* Add classification generated column to account

* Add basic net worth calculation

* Add net worth tests

* Fix lint errors

test/controllers/accounts_controller_test.rb

@@ -3,7 +3,7 @@ require "test_helper"
 class AccountsControllerTest < ActionDispatch::IntegrationTest
   setup do
     sign_in @user = users(:family_admin)
-    @account = accounts(:generic)
+    @account = accounts(:checking)
   end
 
   test "new" do

test/controllers/valuations_controller_test.rb

@@ -3,7 +3,7 @@ require "test_helper"
 class ValuationsControllerTest < ActionDispatch::IntegrationTest
   setup do
     sign_in @user = users(:family_admin)
-    @account = accounts(:generic)
+    @account = accounts(:checking)
   end
 
   test "new" do