Review replace file drop area

Research best option that:

• doesn't have always on a drop area (takes too much space)
• works with other "files" like attachment

Proposed Solution
Look into mockups attached or https://projects.invisionapp.com/freehand/document/3D8jO6dgO

In terms of main file replacement, I would still consider 2 possible behaviors:
A) Action (icon attached) that will reveal a pop up with extended options to upload new file. The icon, if possible, should be ordered right before the remove blob icon.
B) Have a droparea on top of the image-viewer, triggered when a file is dragged on top of it.