sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/sysfs/sysfswrite.hpp b/sysfs/sysfswrite.hpp
index 276d936..615cb37 100644
--- a/sysfs/sysfswrite.hpp
+++ b/sysfs/sysfswrite.hpp
@@ -5,6 +5,9 @@
 
 #include <string>
 
+namespace pid_control
+{
+
 /*
  * A WriteInterface that is expecting a path that's sysfs, but really could be
  * any filesystem path.
@@ -34,3 +37,5 @@
   private:
     std::string _writePath;
 };
+
+} // namespace pid_control