Initial Phablet desktop package and associated deps.
Add phablet-preview and associated deps. to run phablet in windowed mode on desktop
Have unity-base/hud* depend on dev-libs/libdbusmenu[test] to enable build
Add new dependencies unity-base/demo-assets, unity-indicators/indicators-client and unity-lenses/unity-lens-mock
Remove 'test' from dev-libs/libdbusmenu depend as is enabled in libdbusmenu ebuild
Update lttng to 2.2.0, add dev-util/umockdev to mir DEPEND