Images dragged and dropped directly into the editor are stripped when saved

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Edit and interaction 
2. Drag and drop and image directly into the exploration text editor
3. Click save content

What is the expected output? What do you see instead?
Either the image is automatically saved as an image asset or the image is not 
permitted to be dragged and dropped in the first place

What operating system are you using?
Windows8/Chrome

Please provide any additional information below.
This is probably a quirk of the default editor script.

Original issue reported on code.google.com by jamesca...@gmail.com on 12 Jul 2015 at 2:09

[GoogleCodeExporter]

Reference: https://groups.google.com/forum/#!topic/oppia-dev/j733Qy7beFo

I don't actually think this is an Oppia issue. If you open *any* page in a 
browser (Oppia or not), and then drag and drop an image into it, the browser 
will interpret that as a command to display the image, and will move away from 
whatever page it was displaying before. Does that match your experience?

Original comment by s...@seanlip.org on 12 Jul 2015 at 8:05