Add UPower Device interface

Add a YAML description of the UPower Device interface defined at
https://upower.freedesktop.org/docs/Device.html

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: Ib70d6525b913cf06da4e93a53e332487126f1db0
diff --git a/gen/org/freedesktop/meson.build b/gen/org/freedesktop/meson.build
new file mode 100644
index 0000000..1ee0a87
--- /dev/null
+++ b/gen/org/freedesktop/meson.build
@@ -0,0 +1,2 @@
+# Generated file; do not modify.
+subdir('UPower')