Linebreaks mode will result in <Enter> key adding a <br/> element to the
HTML markup rather than starting a new paragraph <p> element.

This patch also changes the behavior of the <Tab> key to change focus away
from the Redactor editor rather than indenting the current block.

Process inline attachments in thread entry and support inline images in
piped emails

Support inline images across the system, with draft support

Migrate to a single attachment table
    That way we don't need a new table for everything we need to attach an
    inline image to (like a signature, for instance)

Add richtext support for internal notes

Implement images on site pages

* Image paste in Redactor
* Make non-local images optional
* Placeholder for non-local images
* Fix local image download hover
* Don't re-attach inline images

The client and scp config ajax request only contain the settings for the
multi-file upload widget. So it doesn't need to be fetched unless the widget
exists on the page

Remove default max limit - no size limit is assumed.

Add overlay & loading spinner to client interface - shown on form submission to help cut down on double submits.