Updated some return value docs to help with autocomplete.
AttachmentModel: Initial Commit
AttachmentModel: add needed style to global style.css
Add support for controllers in plugins.

- Autoload controllers with all autoloader maps.
- When finding a controller check to see if it
  belongs to a plugin or application.
Remove Gdn_Controller->ControllerFolder.

The ControllerFolder is a really old artifact of pre 2.0 Vanilla. It was intended to allow for controllers nested into folders which ended up never being used.
Don’t dispatch to controllers that aren’t in a /controllers folder.
attachments: Only write error attachment if custom methods are enabled
Set the Gdn_Controller->Application to the name of the plugin if
dispatching to a plugin’s controller.
Allow Gdn_Dispatcher->ControllerArgumetns() to take a $Value parameter.
Improve markup of "In This Discussion" list.
Set correct date format.
Remove username styling from panels.
Improve markup of "In This Conversation" list.
Ensure right-floated counts appear before label.

This will allow for proper document flow where the category label can
be truncated using `text-overflow` if need be.
Terminate Declaration Statement in categories.js

Added missing terminator in `/vanilla/applications/vanilla/js/categories.js`.
Merge branch 'master' of github.com:vanilla/vanilla into feature/attachmentmodel

* 'master' of github.com:vanilla/vanilla: (23 commits)
  SSO: added CSS class to Google and OpenID sign in buttons.
  Checkout functions.render changes from stage.
  Version 2.2.12.
  Add a .js-extern css class so that embed will know of links that redirect to external sites.
  Check out logger changes from feature/multisite.
  Fix bug where the log levels are referenced against the wrong object.
  Fix default log level bug.
  Set a default Logger::$logLevel.
  Tweak the spelling/grammar of log messages.
  Add additional log level function to the Logger class.
  Change to use UserName instead of InsertName.
  Revert change to editor config.
  Core: shortened inline comment.
  Core: instead of checking against SocialIcon CSS class, check against a more general CSS class, so that social sign in links in embedded forums are more robust.
  Core: conditionally define target for social sign in anchors for forcefully embedded forums.
  dblogger: Add simple API, Update to use URL with domain,
  Baselogger: fix error log level
  Core: added another condition to linkify/embedify method.
  Core: added config check to disable URL to video embed transformations. This was prompted by a need within the Signatures plugin.
  logger: Added: password_reset and password_reset_request events
  ...
Add spaces after category counts.
AttachmentModel: Refactor method names.
AttachmentModel: Moving css to vanilla controller.
AttachmentModel> Add vanillicon.css with style.css