Bug fix for image size

Supersensor code was falling over when going
through a series of images, because the grid
size (for the geotiff) was only calculated
once per sensor, but some images are one or
two grid points different in size.

(This is because when the region of interest
is extracted, the grid size is calculated
from the original image size)

Move the calculation of grid size inside the
loop for each image, so it is calculated
separately each time. Code now runs ok.

Also, remove some unneeded print commands
that were for debugging.
Update supersensor tests

Amend unit test to include the sun and
viewing azimuth angles in metadata
extraction.