There appears to be a regression in the way bson handles `numpy.int64` and `numpy.float64` values.

Works in 2.7

{{In [2]: sys.version
Out[2]: '2.7.11 |Anaconda 2.0.1 (x86_64)| (default, Dec 6 2015, 18:57:58) \n[GCC 4.2.1 (Apple Inc. build 5577)]'

In [3]: import bson.json_util as bju

In [4]: import numpy as np

In [5]: bju.dumps(

{'a': np.int64(12345)}

)
Out[5]: '

{"a": 12345}

'
}}

Fails in 3.6

{{In [69]: import sys

In [70]: sys.version
Out[70]: '3.6.2 |Anaconda custom (x86_64)| (default, Jul 20 2017, 13:14:59) \n[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)]'

In [71]: import bson.json_util as bju

In [72]: import numpy as np

In [73]: bju.dumps(

{'a': np.int64(12345)}

)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-73-03e5f501a15a> in <module>()
----> 1 bju.dumps(

{'a': np.int64(12345)}

)

/Users/shankari/OSS/anaconda/envs/py36/lib/python3.6/site-packages/bson/json_util.py in dumps(obj, *args, **kwargs)
401 """
402 json_options = kwargs.pop("json_options", DEFAULT_JSON_OPTIONS)
--> 403 return json.dumps(_json_convert(obj, json_options), *args, **kwargs)
404
405

/Users/shankari/OSS/anaconda/envs/py36/lib/python3.6/json/_init_.py in dumps(obj, skipkeys, ensure_ascii, check_circular, allow_nan, cls, indent, separators, default, sort_keys, **kw)
229 cls is None and indent is None and separators is None and
230 default is None and not sort_keys and not kw):
--> 231 return _default_encoder.encode(obj)
232 if cls is None:
233 cls = JSONEncoder

/Users/shankari/OSS/anaconda/envs/py36/lib/python3.6/json/encoder.py in encode(self, o)
197 # exceptions aren't as detailed. The list call should be roughly
198 # equivalent to the PySequence_Fast that ''.join() would do.
--> 199 chunks = self.iterencode(o, _one_shot=True)
200 if not isinstance(chunks, (list, tuple)):
201 chunks = list(chunks)

/Users/shankari/OSS/anaconda/envs/py36/lib/python3.6/json/encoder.py in iterencode(self, o, _one_shot)
255 self.key_separator, self.item_separator, self.sort_keys,
256 self.skipkeys, _one_shot)
--> 257 return _iterencode(o, 0)
258
259 def _make_iterencode(markers, _default, _encoder, _indent, _floatstr,

/Users/shankari/OSS/anaconda/envs/py36/lib/python3.6/json/encoder.py in default(self, o)
178 """
179 raise TypeError("Object of type '%s' is not JSON serializable" %
--> 180 o._class.name_)
181
182 def encode(self, o):

TypeError: Object of type 'int64' is not JSON serializable

}}

This complicates interfacing with pandas because pandas returns values in `numpy.int64` and `numpy.float64`.