Fix runtime error on osx

[nishi-t]

I get following error when run a tvm sample code on osx after build master and install it by python setup.py install. I'm not sure, but fixed my error by changing "package_data": {'tvm': LIB_LIST} to "data_files": [('tvm', LIB_LIST)].
@abergeron @tqchen Could you review this?

Error message

$ python tvm_sample.py
Traceback (most recent call last):
  File "/Users/tatsuya/misc/nnvm/samples/tvm_concat.py", line 2, in <module>
    import topi
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/topi-0.4.0-py3.6.egg/topi/__init__.py", line 12, in <module>
    from tvm._ffi.libinfo import __version__
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/__init__.py", line 5, in <module>
    from . import tensor
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/tensor.py", line 4, in <module>
    from ._ffi.node import NodeBase, NodeGeneric, register_node, convert_to_node
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/_ffi/node.py", line 8, in <module>
    from .node_generic import NodeGeneric, convert_to_node, const
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/_ffi/node_generic.py", line 7, in <module>
    from .base import string_types
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/_ffi/base.py", line 43, in <module>
    _LIB, _LIB_NAME = _load_lib()
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/_ffi/base.py", line 34, in _load_lib
    lib_path = libinfo.find_lib_path()
  File "/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/_ffi/libinfo.py", line 93, in find_lib_path
    raise RuntimeError(message)
RuntimeError: Cannot find the files.
List of candidates:
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/libtvm.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/build/libtvm.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/build/Release/libtvm.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/lib/libtvm.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/libtvm.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/tvm-0.4.0-py3.6-macosx-10.13-x86_64.egg/tvm/libtvm_runtime.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/build/libtvm_runtime.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/build/Release/libtvm_runtime.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/site-packages/lib/libtvm_runtime.dylib
/Users/tatsuya/venv/nnvm-dev/lib/python3.6/libtvm_runtime.dylib

[tqchen]

I am going to go ahead and merge this in for now

[tqchen]

After looking at the docs, seems that both data_files and package_data should be fine, maybe data_files is more generalized