Fix fatal crash when adding a new page

Also add images on pages to the drop-down list for image choosing, and fix
display of images on the client portal.
Add `type` column to site pages listing
External URLs need to route through l.php

This include URLs in embedded links as well as URLs for external images and
videos embedded via iframe elements.
Ensure sane and consistent styling

Fix width of the ticket thread body
Add consistent font styling between Redactor and thread body
Merge pull request #146 from greezybacon/issue/131

Fix a few things related to site pages

Reviewed-By: Peter Rotich <peter@osticket.com>
Merge pull request #151 from greezybacon/issue/61

External URLs need to route through l.php

Reviewed-By: Peter Rotich <peter@osticket.com>
Merge pull request #152 from greezybacon/issue/137

Ensure sane and consistent styling

Reviewed-By: Peter Rotich <peter@osticket.com>
Fix M$ styling for lists

Previously list items rendered outside the thread-body table cell
Regression: restore l.php Referrer cloaking
Remove old or unnecessary configuration settings
Make max_upload_filesize a drop-down list
Merge pull request #154 from greezybacon/issue/config-cleanup

Cleanup configuration prior to stable release

Reviewed-By: Peter Rotich <peter@osticket.com>