add macro for numpy < 1.7

as suggested by @longjon
https://github.com/BVLC/caffe/issues/44#issuecomment-32832810

python/caffe/pycaffe.cpp

@@ -10,9 +10,11 @@
 #include <numpy/arrayobject.h>
 #include "caffe/caffe.hpp"
 
-// Temporary solution for numpy < 1.7 versions: old macro.
+// Temporary solution for numpy < 1.7 versions: old macro, no promises.
+// You're strongly advised to upgrade to >= 1.7.
 #ifndef NPY_ARRAY_C_CONTIGUOUS
 #define NPY_ARRAY_C_CONTIGUOUS NPY_C_CONTIGUOUS
+#define PyArray_SetBaseObject(arr, x) (PyArray_BASE(arr) = (x))
 #endif