[bug] namespace comparison for numpy objects

[L-in-da]

Solves the following issue:

from datamate import Namespace
import numpy as np

config1 = Namespace(
    a=np.float64(1.0),
)
config2 = Namespace(
    a=1.0,
)
print(config1 == config2)  

The comparison raises the error: TypeError: all True of type <class 'numpy.bool'>: vars() argument must have __dict__ attribute.

For more details, see discussion in #20
Closes #20

[lappalainenj]

Great, thanks!