Integrated new audit permissions with the UI

The app now supports audit-specific roles. 

- Audits have their own unique context, with which all other requests and responses are bound to.
- Audit roles may be applied via the Auditors link in every audit (pops up an authorizations dialog).
- Added permission enforcement to audit UI elements (like audit reader can't edit values).

IMPORTANT: Any audits created with older code will no longer work due to the new permission structure!