Remove unused resource class methods
Fix property renaming using fields.Raw(attribute="xyz")
added simple examples for principals use and authentication

Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net>
updated example with fixes from #8

Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net>
improvements based on comments

 * changed ‘lambda’ into ‘user’
 * default to redirect to ‘/book’
 * removed session tampering

Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net>