Improved Shiro Filter configuration for Spring environments

A Spring-specific ShiroFilter would allow Spring configuration of the Filter properties, along with any nested filters and filter chain definitions, enabling a more powerful Dependency Injection mechanism that what is available with the INI configuration alone.

This task will track creating a ShiroFilterFactoryBean that allows Spring-only configuration for the Filter, without needing INI configuration (but while still being as easy to configure as INI)