remove warning on feather for pandas >= 0.20.1

[asfimport]

In [9]: import pyarrow

In [10]: pyarrow.version
Out[10]: '0.4.0'

In [11]: df = pd.DataFrame({'A':['foo']})

In [12]: df.to_feather('foo.fth')
/Users/jreback/miniconda3/envs/pandas/lib/python3.6/site-packages/pyarrow/feather.py:78: FutureWarning: pandas.lib is deprecated and will be removed in a future version.
You can access infer_dtype as pandas.api.types.infer_dtype
inferred_type = pd.lib.infer_dtype(col)

Resolved here:

#715

Reporter: Jeff Reback / @jreback
Assignee: Jeff Reback / @jreback

_{Note: This issue was originally created as ARROW-1066. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 715
#715