Access control on Springboard Views

## Changes
 - Adds permission checks on sbv_notes and sbv_administrators Views.
 - Adds a hook_requirements implementation for Springboard Views to check if anonymous users can access the springboard views. Provides an error on the status report and the name of the Views.

## Deploy details
 - Existing sites that have not customized sbv_notes or sbv_administrators should clear the caches to get the new access control. Simply clear caches after updating code and check the status report to see that the change happened.
 - If Views UI is enabled, go to the Views page, click the dropdown arrow next to the Edit link for each of these Views, and click Revert. This will wipe out any customizations to those Views.