Device Controls for Harmony UI

[mschwartz]

An activity might include TV, TiVo, and AVR. From the TiVo controls, you should be able to select one of those and be able to control it. We already have direct control over TV, TiVo, and AVR. Maybe hook into those. In some cases, Harmony control is necessary (e.g. an AVR that has no internet/WiFi or API).