added option to resample png and tiff files
Added deseasonalizing routine
Bounding box for tiff, png image files
created imagefile bounding box function
bugfix
Merge branch 'develop' of https://github.com/IsabellaP/poets into IsabellaP-develop

Conflicts:
	poets/image/resampling.py
Merge branch 'IsabellaP-develop' into develop