Raise error on unpermitted params.

Fail loudly if we forget to whitelist a param instead of silently
ignoring it.

misc models: convert to strong params.

artist commentaries: convert to strong params.

* Disallow changing or setting post_id to a nonexistent post.

artists: convert to strong params.

* Disallow setting `is_banned` in create/update actions. Changing it
  this way instead of with the ban/unban actions would leave the artist in
  a partially banned state.

bans: convert to strong params.

* Disallow changing the user_id after the ban has been created.

comments: convert to strong params.

favorite groups: convert to strong params.

news updates: convert to strong params.

post appeals: convert to strong params.

post flags: convert to strong params.

* Disallow users from setting the `is_deleted` / `is_resolved` flags.

ip bans: convert to strong params.

user feedbacks: convert to strong params.

* Disallow users from setting `disable_dmail_notification` when creating feedbacks.
* Disallow changing the user_id after the feedback has been created.

notes: convert to strong params.

wiki pages: convert to strong params.

* Also fix non-Builders being able to delete wiki pages.

saved searches: convert to strong params.

pools: convert to strong params.

* Disallow setting `post_count` or `is_deleted` in create/update actions.

janitor trials: convert to strong params.

post disapprovals: convert to strong params.

* Factor out quick-mod bar to shared partial.
* Fix quick-mod bar to use `Post#is_approvable?` to determine visibility
  of Approve button.

dmail filters: convert to strong params.

password resets: convert to strong params.

user name change requests: convert to strong params.

posts: convert to strong params.

users: convert to strong params.

* Disallow setting password_hash, last_logged_in_at, last_forum_read_at,
  has_mail, and dmail_filter_attributes[user_id].

* Remove initialize_default_image_size (dead code).

uploads: convert to strong params.

* Remove `initialize_status` because status already defaults to pending
  in the database.

tag aliases/implications: convert to strong params.

tags: convert to strong params.

forum posts: convert to strong params.

* Disallow changing the topic_id after creating the post.
* Disallow setting is_deleted (destroy/undelete actions should be used instead).
* Remove is_sticky / is_locked (nonexistent attributes).

forum topics: convert to strong params.

* merges https://github.com/evazion/danbooru/tree/wip-rails-5.1
* lock pg gem to 0.21 (1.0.0 is incompatible with rails 5.1.4)
* switch to factorybot and change all references

Co-authored-by: r888888888 <r888888888@gmail.com>
Co-authored-by: evazion <noizave@gmail.com>

add diffs

app/views/pool_versions/_standard_listing.html.erb

@@ -15,7 +15,7 @@
     </thead>
     <tbody>
       <% @pool_versions.each do |pool_version| %>
-        <tr>
+        <tr id="pool-version-<%= pool_version.id %>">
           <td><%= link_to pool_version.pretty_name, pool_path(pool_version.pool_id), :class => "pool-category-#{pool_version.pool.category}" %></td>
           <td><%= link_to pool_version.post_ids.size, pool_versions_path(:search => {:pool_id => pool_version.pool_id}) %></td>
           <td class="col-expand"><%= pool_version_diff(pool_version) %></td>