Add support for anonymous login to OpenAnzo

[jordi]

Sometimes, people want to build applications that can be accessed without a username/password. One way to do that is to just use a hard-coded username and password. But that causes difficulties with managing appropriate access control when you want some things private and some things accessible anonymously.

We want to add some built-in support to help application developers for this. The support includes:

• a built-in anzo_anonymous user which will login with any password.
• a configuration option org.openanzo.security.ldap.anonymousAccessEnabled in the org.openanzo.security.ldap.LdapAuthentication service to turn anonymous access on and off. It's off by default.
• protections in the update server to prevent anonymous users from creating/updating/deleting data.

[jordi]

(In [5229]) refs #881. Add support for anonymous access to the server.

[jordi]

(In [5230]) refs #881. Fix classpath to make test compile in Eclipse.

[jordi]

(In [5236]) refs #881. Reuse a constant that already existed and allow playback as anonymous.

[jordi]

(In [5246]) refs #881. Add support for anonymous access to the server. This foreports changes from [5229],[5230],[5236].

[jordi]

Jason, please review.