Fix test in module tests.robottelo.test_ssh

* Fix all references to the instance variable `Config._properties`.
* Populate the config file dictionary with test values.
* Create a DSA private key for test purposes
Make API docs reference recently added module
Reorder API documentation content

If a package contains any sub-packages, links to those sub-packages should
appear at the very top of the relevant documentation. This is in line with user
expectations: navigation elements typically appear above content.