Fix issue #10: Load Sites_Schema class in Sunrise to prevent database errors

[marcusquinn]

@superdav42 Updates this PR to only address the database classes issue (#10) and remove the textdomain loading changes.

I'll create a separate PR for the textdomain loading fix (#15) to maintain clean separation of concerns.

Fix issue #10: Load Sites_Schema class in Sunrise to prevent database errors

Description

This PR addresses issue #10 where users were experiencing database errors due to missing database classes. The error occurs because the Sites_Schema class is not loaded early enough in the Sunrise process.

Changes Made

• Added a require statement in the Sunrise class to load the Sites_Schema class
• Removed a duplicate require statement for the Theme_Limits class

Benefits

• Prevents database errors when accessing sites
• Ensures all necessary database classes are loaded before they're needed
• Improves overall stability of the plugin

Testing

1. Install the plugin on a fresh WordPress multisite installation
2. Create a new site
3. Verify that no database errors occur when accessing the site

Fixes #10