Gordo client - allow supplying data directly to the predict function

[flikka]

Today, you supply a data provider. But some users we have would like to directly provide the needed "dataframe" for a given Gordo model when doing .predict()

Note - be aware that the pandas.from_dict() sorts your frame according to the index. If this index is a string, but are actually row numbers - it will become wrong. This has been seen in the wild