Various bug fixes

API Changes

• The October\Rain\Database\Attach\File model now uses "fillable" attributes as opposed to "guarded" attributes to control mass assignment. If you extend the File (or the main System\Models\File) model to provide additional fields, you must now copy the "fillable" attributes to your extension and add any additional fields to this definition.

Bug Fixes

• Temporarily fixed an issue with existing code-bases that abuse the Twig engine by loading template files in unsupported ways (.js / .svg files rendered as partials through {% partial %}, {% include %}, or $this->renderPartial()). NOTE: This hotfix will not be available in Build 1.1.x so existing code still needs to be fixed to not use those unsupported file types.
• Fixed an issue introduced in Build 1.0.469 where plain Twig templates couldn't be loaded through the {% include 'path' %} or {{ source(path) }} Twig functions
• Fixed issue introduced in a security update to Laravel 5.5 where models with guarded properties were failing to allow attributes that don't have a corresponding column to be processed in events (for example, the "data" attribute in the File model).

Security Improvements

• Tightened up the default permissions granted to the "Publisher" system role out of the box.
• Locked down the Twig sandbox even more to prevent allowing users with access to Twig templates from defining and running PHP code.