sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/dbus/dbuswrite.hpp b/dbus/dbuswrite.hpp
index b8a6035..5cc2d49 100644
--- a/dbus/dbuswrite.hpp
+++ b/dbus/dbuswrite.hpp
@@ -24,6 +24,9 @@
 #include <memory>
 #include <string>
 
+namespace pid_control
+{
+
 class DbusWritePercent : public WriteInterface
 {
   public:
@@ -65,3 +68,5 @@
     std::string connectionName;
     int64_t oldValue = -1;
 };
+
+} // namespace pid_control