sensors: split building from manager object

To increase testability, split out the building of sensors
from the sensor manager.  And this further splits out building
from a configuration file.

Tested: Verified code continued to build and link.
Tested: Ran on quanta-q71l board and it behaved as expected.

Change-Id: Ib63a11e1107b1864c3c370bba2bd9ef2effa42f3
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/sensors/builderconfig.hpp b/sensors/builderconfig.hpp
new file mode 100644
index 0000000..078f484
--- /dev/null
+++ b/sensors/builderconfig.hpp
@@ -0,0 +1,12 @@
+#pragma once
+
+#include <memory>
+#include <string>
+
+#include "sensors/manager.hpp"
+
+/**
+ * Given a configuration file, parsable by libconfig++, parse it and then pass
+ * the information onto BuildSensors.
+ */
+std::shared_ptr<SensorManager> BuildSensorsFromConfig(const std::string& path);