Anonymous access and default_policy management

 - Set default_policy to anonymous,
 - Remove others: to use system.Everyone and system.Authenticated instead,
 - Add make tests-failfast to run test on py27 with -x and -s options
 - Read default_policy form pserve ini file.
 - Use read-only default_policy in test
 - Use anonymous default_policy in development as for daybed 0.1
 - Add test for BasicAuth user creation
 - Add test for forbidden json page