Expand conf namespace

Put rest of conf.hpp in the conf namespace. This is
largely a sed replace, and wrapping from_json in
conf namespace as it failed to build.

Change-Id: I9fe5c7b2fface44618c43af2367035afc39bcb64
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/sensors/builder.hpp b/sensors/builder.hpp
index d646223..224d467 100644
--- a/sensors/builder.hpp
+++ b/sensors/builder.hpp
@@ -9,5 +9,5 @@
 /**
  * Build the sensors and associate them with a SensorManager.
  */
-SensorManager
-    buildSensors(const std::map<std::string, struct SensorConfig>& config);
+SensorManager buildSensors(
+    const std::map<std::string, struct conf::SensorConfig>& config);