Genesis plugin configuration check

[bugzmanov]

Background: Several genesis plugins depends heavily on configuration (email, ldap, jclouds).
System admin has to do complex actions to verify configuration. These actions are different for different plugins.

In order to improve configuration validationd for system admins, genesis plugins should provide means to smoke test own configuration.

Note: this story is independent from static validation, cause require some implementation specific actions to be performed by plugin.