Add userland-software unit to Salt Top file

Summary:
This unit is now ready to run in production,
so Eglide will pick up changes at regular intervals.

This is a follow-up for b2e551f238fc and 0f6e08c82898.

Test Plan: salt eglide state.apply, output available at P189.

Reviewers: Sandlayth

Differential Revision: http://devcentral.nasqueron.org/D358