approve button doesn't update reference image in UI

I am seeing an issue where using approve button doesn't update reference image in the report UI -- however, it does successfully run the `approve` on the back end -- so this is just a UI issue.

This is most noticeable when you've run backstop for the first time as with the sanity test described here... https://github.com/garris/BackstopJS#sanity-test-does-backstop-work-in-my-environment

Here is what it looked like for me. I expected the reference image column to be updated with the test image...

Run this command to try it yourself...
```
mkdir backstopSanityTest; cd backstopSanityTest; npm install backstopjs; node ./node_modules/backstopjs/cli/ init; node ./node_modules/backstopjs/cli/ remote & node ./node_modules/backstopjs/cli/ test && fg
```
_The above script will create a test directory, install backstop, start a remote process and run a test. Once the test completes it the terminal will bring the remote process to the foreground so you can kill it when you're done testing._