Annotation Tools: Removed background-color from image annotations

**Priority is HIGH for this PR since the course is currently live and the share functionality is not working properly.**

**Background:** This is a feature fix for the Image annotation tool. Because of the overlays, whenever too many people annotated the image would be hidden behind the yellow colors. Background colors were ditched in favor of the border being the designated item. A bug also has been fixed which didn't allow you to Edit an annotation until another one had been created. 

**CMS Updates:** None.

**LMS Updates:** Minimal. Check to make sure that background is removed when image annotations are made. There should be a slight yellow tint during hover and when clicking the thumbnail in the table below. You should now also be able to edit an annotation when page loads instead of having to create an annotation, delete it and edit the original one. 

**Testing: ** Basically follow instructions above. Critical change for the purposes of people being able to see the image hidden underneath all annotations. 
Thank you, that's quite a relief and forgive the frustration.