df.to_parquet crashes on pyarrow with timedelta64[ns]
#### Code Sample, a copy-pastable example if possible

```python
# any dataframe with a timedelta64[ns] type in it
df.to_parquet('/tmp/tmp.parquet.gzip', compression='gzip')  
```

versions:
```
Python 3.7.6
pandas==0.25.3
pyarrow==0.15.1
```

#### Problem description

```
Traceback (most recent call last):
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/site-packages/pandas/core/frame.py", line 2237, in to_parquet
    **kwargs
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/site-packages/pandas/io/parquet.py", line 254, in to_parquet
    **kwargs
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/site-packages/pandas/io/parquet.py", line 101, in write
    table = self.api.Table.from_pandas(df, **from_pandas_kwargs)
  File "pyarrow/table.pxi", line 1057, in pyarrow.lib.Table.from_pandas
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/site-packages/pyarrow/pandas_compat.py", line 560, in dataframe_to_arrays
    convert_fields))
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/concurrent/futures/_base.py", line 598, in result_iterator
    yield fs.pop().result()
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/concurrent/futures/_base.py", line 428, in result
    return self.__get_result()
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/concurrent/futures/_base.py", line 384, in __get_result
    raise self._exception
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/site-packages/pyarrow/pandas_compat.py", line 546, in convert_column
    raise e
  File "/opt/conda/envs/gis-dataprocessing/lib/python3.7/site-packages/pyarrow/pandas_compat.py", line 540, in convert_column
    result = pa.array(col, type=type_, from_pandas=True, safe=safe)
  File "pyarrow/array.pxi", line 207, in pyarrow.lib.array
  File "pyarrow/array.pxi", line 74, in pyarrow.lib._ndarray_to_array
  File "pyarrow/array.pxi", line 62, in pyarrow.lib._ndarray_to_type
  File "pyarrow/error.pxi", line 86, in pyarrow.lib.check_status
pyarrow.lib.ArrowNotImplementedError: ('Unsupported numpy type 22', 'Conversion failed for column elapsed_time with type timedelta64[ns]')
```

PS, Submitting an issue on pyarrow in JIRA is a complete 🤕  😞 
