Simplify example for zend.session.manager

[adamlundrigan]

The current example is very complex:

http://zf2.readthedocs.org/en/latest/modules/zend.session.manager.html#initializing-the-session-manager

IMO the SessionManagerFactory provided by ZF2 would take care of most of this boilerplate.

An example of how I approach configuring the SessionManager in my projects: ZF-Commons/ZfcUser#274 (comment). In that example, we could pass configuration options (eg: validator list) to the SessionManager factory via the session_manager config key.

[Martin-P]

SessionManagerFactory is indeed easier to use, however there is a problem with adding validators via config at this moment: zendframework/zendframework#7128

[xelax90]

The Issue seems to be fixed, so the example could be simplified now