Fixes to python bindings instalation

src/python/CMakeLists.txt

-configure_file(
-    ${CMAKE_CURRENT_SOURCE_DIR}/setup.py.tpl 
-    ${CMAKE_CURRENT_SOURCE_DIR}/setup.py
-)
+configure_file( setup.py.tpl setup.py )
 
-if (NOT DEFINED PYTHON_INSTALL_PREFIX)
-    set(PYTHON_INSTALL_PREFIX ${CMAKE_INSTALL_PREFIX})
-endif()
+install( DIRECTORY pyflann DESTINATION share/flann/python )
+install( FILES ${CMAKE_CURRENT_BINARY_DIR}/setup.py DESTINATION share/flann/python )
 
-install(CODE "execute_process(
-    COMMAND ${PYTHON_EXECUTABLE} setup.py install --prefix ${PROJECT_BINARY_DIR}/python_install --install-layout deb
-    WORKING_DIRECTORY \"${CMAKE_CURRENT_SOURCE_DIR}\")")
 
-install (
-    DIRECTORY ${PROJECT_BINARY_DIR}/python_install/
-    DESTINATION ${CMAKE_INSTALL_PREFIX} 
-)
+# python instalation
+if (PYTHON_EXECUTABLE)
+    install(CODE "execute_process(
+        COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/setup.py install
+        WORKING_DIRECTORY \"${CMAKE_CURRENT_SOURCE_DIR}\")")
+endif()