JSON Serializing Fails on Decimal

[tarzzz]

The default JSON serializer is not able to serialize Decimal objects.
Exact traceback from a use case:

Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/plotly/plotly/plotly.py", line 241, in plot
    res = _send_to_plotly(figure, **plot_options)
  File "/Library/Python/2.7/site-packages/plotly/plotly/plotly.py", line 1374, in _send_to_plotly
    cls=utils.PlotlyJSONEncoder)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 250, in dumps
    sort_keys=sort_keys, **kw).encode(obj)
  File "/Library/Python/2.7/site-packages/plotly/utils.py", line 145, in encode
    encoded_o = super(PlotlyJSONEncoder, self).encode(o)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 207, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 270, in iterencode
    return _iterencode(o, 0)
  File "/Library/Python/2.7/site-packages/plotly/utils.py", line 211, in default
    return json.JSONEncoder.default(self, obj)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 184, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: Decimal('-94.6285553000') is not JSON serializable

[tarzzz]

To reproduce the error:

import plotly.plotly as py
import decimal
x = [decimal.Decimal(i) for i in range(100)]
import numpy as np
y = [decimal.Decimal(i) for i in np.random.randint(1,100,100)]
trace = dict(x=x,y=y,type='scatter',mode='markers')
py.plot([trace])