Image region image does not properly support different labels

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Create a state with the image region interaction
2. Add an image to it
3. Add 1 region and give it a label with text (such as "label")
4. Try to add a response with a rule targeting that label

What is the expected output? What do you see instead?
The rule should say "is in region label" and there should be no errors. 
Instead, it says "is in region [INVALID]" and there are errors preventing 
saving the exploration (likely a validation error). If the region is named "1", 
however, everything works as expected.

Original issue reported on code.google.com by bhenn...@google.com on 31 Jul 2015 at 4:28

[GoogleCodeExporter]

As a follow-up: Initially adding a rule for any label seems to also cause an 
error until you manually expand the rule and save it (even if no changes are 
made).

Original comment by bhenn...@google.com on 31 Jul 2015 at 4:29