Dynamic change of image.

[AndriyZaec]

@ikorich
Need possibility, to change the image dynamically. Cause I use your library in my VIPER project with custom navigation I need to set an image placeholder at first, and on completion set real image that I want to crop.

Questions:

• Can your library handle it?
• Maybe am I doing something wrong?
• If not your suggestions on how to do it without changing of library concept?

P.S. I'll make PR with your suggestions to fix this.

Thank you in advance.