Fixes bases on updates to numpy and scikit-image

[aryabhatt]

Changes proposed in this pull request:

• np.int changed to int i
• np.Inf changed to np.inf
• removed a keyword argument from skimage.transform.rescale
• added requirements.txt

Fixes issue

• works with current versions of numpy and scikit-image.
• should be pip installable, if using CPython instead of Anaconda

Checklist:

• [ ] Update CHANGELOG.md