memory: Hide all copy/assignment ops for class w/heap allocation

Many of the UPM libraries allocate space on the heap but do not
explicitly handle copying and assignment.  This commit uses C++11 delete
to forbit both the copy and assignment operator for these classes.

The C++ examples which used assignment operators to initialize class
instances were also updated since it did not appear necessary in those
cases to use the assignment operator.

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/stepmotor/stepmotor.hpp

@@ -154,6 +154,10 @@ class StepMotor {
         int getStep ();
 
     private:
+        /* Disable implicit copy and assignment operators */
+        StepMotor(const StepMotor&) = delete;
+        StepMotor &operator=(const StepMotor&) = delete;
+
         std::string         m_name;
 
         mraa::Gpio          m_dirPinCtx;