Added initial interfaces and some sensors implementing them

Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/maxsonarez/maxsonarez.hpp

@@ -26,6 +26,7 @@
 #include <iostream>
 #include <string>
 #include <mraa/aio.h>
+#include <interfaces/iDistance.hpp>
 
 // EZ series is volts/512
 #define MAXSONAREZ_RES  512
@@ -67,7 +68,7 @@ namespace upm {
    * @snippet maxsonarez.cxx Interesting
    */
 
-  class MAXSONAREZ {
+  class MAXSONAREZ : virtual public iDistance {
   public:
 
     /**
@@ -90,6 +91,13 @@ namespace upm {
      */
     int inches();
 
+    /**
+     * Gets the distance to the object in inches
+     *
+     * @return Distance to the object in inches
+     */
+    virtual int getDistance();
+
   private:
     mraa_aio_context m_aio;
     float m_aref;