Sensor Objects

This includes all the sensor objects including a few
implementations, including dbus and sysfs sensors.

Change-Id: I9897c79f9fd463f00f0e02aeb6c32ffa89635dbe
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/dbus/README b/dbus/README
new file mode 100644
index 0000000..dd079d8
--- /dev/null
+++ b/dbus/README
@@ -0,0 +1,7 @@
+# DbusPassive
+
+These sensors wait for their updates.
+
+# DbusActive
+
+These sensors reach out for their value.