Adding SWIG guarder to InterpolatorEnum output operator

Using macro in Interpolator output operator

Change-Id: Ieae7a5bf745a3d4a4b6b5ee89e35d7c478e64c85
Adding test of Interpoaltor enum output operator

Change-Id: I4060592b8045204dd78602500c04e65f83793a30
Merge topic 'SIMPLEITK-430_PrintIterpolatorsAsStrings' into next

12e44d02 Adding test of Interpoaltor enum output operator
655431da Adding SWIG guarder to InterpolatorEnum output operator