Fix Python 2 bindings support in CMake scripts

#57 introduced two issues:
 * wrong name for the variable that holds Boost Python component;
 * unconditional search for `python3`.

python/CMakeLists.txt

@@ -43,8 +43,7 @@ if (PYTHONLIBS_FOUND AND PYTHONINTERP_FOUND)
 		endif(PYTHON_VERSION_MAJOR GREATER 2)
 	endif (PYTHON_DEB_INSTALL_TARGET)
 
-	find_package(Boost COMPONENTS ${BOOST_PYTHON_PACKAGE} python3)
-	message(Boost_PYTHON3_FOUND found: ${Boost_PYTHON3_FOUND}})
+	find_package(Boost COMPONENTS ${BOOST_PYTHON_COMPONENT})
 	find_python_module(numpy)
 	find_package_handle_standard_args(numpy DEFAULT_MSG PY_NUMPY)
 	if (Boost_FOUND AND NUMPY_FOUND)