Remove the reassign column from issue_comments

Reassigning is an effect of a controller action, not something that
should be stored in the database like this.

db/migrate/20160822153115_create_issue_comments.rb

@@ -4,7 +4,6 @@ class CreateIssueComments < ActiveRecord::Migration[5.0]
       t.integer :issue_id, :null => false
       t.integer :commenter_user_id, :null => false
       t.text :body, :null => false
-      t.boolean :reassign
       t.timestamps :null => false
     end
 

db/structure.sql

@@ -694,7 +694,6 @@ CREATE TABLE issue_comments (
     issue_id integer NOT NULL,
     commenter_user_id integer NOT NULL,
     body text NOT NULL,
-    reassign boolean,
     created_at timestamp without time zone NOT NULL,
     updated_at timestamp without time zone NOT NULL
 );