Dismiss "Code Snippet" modal by clicking outside modal

[mapninja]

Currently, use the X of esc key to exit "Code Snippet" modal (and perhaps others). Many users, myself included, expect the modal to be dismissed if you click outside the modal and on the page it is superimposed on. Might not be possible for accessibility reasons, but if it is, it would be nice to add this behavior.

[dnoneill]

Since we are using the blacklight modal for this feature I am going to suggest we fix this in blacklight that way all our apps can get the benefits of this feature.

[dnoneill]

should be closed with projectblacklight/blacklight#3489