Convert documentation of _prepare_template_tags to docstring.
Add image filter.
Fix image filter declaration.
Change key names of images variables and dict name where they are stored.
image_filter now support args and kwargs.
First draft for image support.
Update documentation.
fs_loader now accepts a file object as a possible value o media.
Updated image support documentation.
Add version history to readme.
Update pypi documentaion.
Update library version.
merge with changes in master