SD-357 Implement method(non REST, python method) to upload image to content archive

SD-357 Implement method(non REST, python method) to upload, process and save a binary image on content archive by using a URL
SD-358 Implement method(non REST, python method) refetch an rendition for an content archive item
I've started testing this feature using unittest instead of behave but because I had to mock a lot of functionality from Eve, I've switched to behave and created and entry-point in the API through which to call the added functionality.