Updated skeleton for os.symlink to be consistent with 3.4 docs (https://docs.python.org/3.4/library/os.html#os.symlink)
Note that I don't know how to represent the signature:
`os.symlink(source, link_name, target_is_directory=False, *, dir_fd=None)`
and keep Python 2 compatibility so I represented:
`os.symlink(source, link_name, target_is_directory=False, dir_fd=None)`
instead.
Merge pull request #5 from lhole/master

Update os.symlink skeleton to Python 3.4