[OBJ] Add basic objective function and registry

src/objective/objective.cc

@@ -0,0 +1,17 @@
+/*!
+ * Copyright 2015 by Contributors
+ * \file objective.cc
+ * \brief global objective function definition.
+ */
+#include <xgboost/objective.h>
+
+namespace dmlc {
+DMLC_REGISTRY_ENABLE(::xgboost::ObjFunctionReg);
+}  // namespace dmlc
+
+namespace xgboost {
+/*! \brief namespace of objective function */
+namespace obj {
+}  // namespace obj
+}  // namespace xgboost
+