LocalFileSystem clobbers file permissions after cp_file #1524

Hi,

I am trying to copy a local file with the following permissions:

-rwxrwxr-x 1 rhorvath rhorvath 7994 

after copying the file it becomes:

-rw-rw-r--  1 rhorvath rhorvath 7994

I have narrowed the reason for this down to the cp_file function in LocalFileSystem where shutil.copyfile(path1, path2) doesn't copy the permission mode. This could be solved by using shutil.copy() and preserving the source file's permission mode.