resampling with one value does not result in a square image

[Rebecca W. Perry]

In the resampling examples given below, the second one doesn't work as expected. The expected output is that h would be [300x300] and the spacing with be [ 0.05466667 0.05466667]. Instead, the image is just shrunk along the first axis.

import holopy as hp
from holopy.core import ImageSchema, Optics

optics = hp.core.Optics(wavelen=.532, index=1.405,
                        polarization=[1.0, 0.0])

#resampling with both dimensions explicitly specified:
h = hp.core.marray.Image(zeros([400,400]), spacing = .041, optics = optics)
h = h.resample([300,300])
print h.spacing

#resampling with just one number:
h = hp.core.marray.Image(zeros([400,400]), spacing = .041, optics = optics)
h = h.resample(300)
print h.spacing