Performance tweaks

Adds schema caching for the restyii schema itself.

Overrides the parent implementations of `CController::resolveViewFile()`, `CWebApplication::createController()` and `CWebApplication::setBasePath()` to avoid touching the file system on each request. These changes mean breaking some compatibility with normal Yii apps:

1. Controllers in subfolders are no longer supported, but I've never seen anyone actually do this anyway.

2. Yii application base path is no longer verified, but I've never seen anyone actually mess this up anyway.

3. localized view files are no longer *automatically* supported - this is a sticky point, but the default implementation is extremely inefficient, with each view or partial render requiring a disk seek. In future we should add a `viewMap` similar to a `classMap` to deal with this.

4. `controllerNamespace` works slightly differently because of point 1.