Add tach sensors to each fan enclosure

Create a tach sensor instance for each sensor listed within a fan
enclosure that uses 'tach' based presence detection. Each tach sensor
has a pointer to the fan it's associated with and is added to the list
of sensors for that fan enclosure.

Change-Id: I9a83ec52d1a5d01e39702e185336a09edeb4d158
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/sensor_base.hpp b/sensor_base.hpp
index 92f53a7..2dc2b8d 100644
--- a/sensor_base.hpp
+++ b/sensor_base.hpp
@@ -19,9 +19,19 @@
         Sensor& operator=(Sensor&&) = delete;
         virtual ~Sensor() = default;
 
+        Sensor(const std::string& id,
+               FanEnclosure& fanEnc) :
+            id(id),
+            fanEnc(fanEnc)
+        {
+            //Nothing to do here
+        }
+
         virtual bool isPresent() = 0;
 
     protected:
+        const std::string id;
+        FanEnclosure& fanEnc;
 
 };