non-logged in user shouldn't be able to unmap application terms

[TravisWalterLBNL]

Without logging in, I clicked on a public application term in a public application, and the application term was mapped to a composite term. I clicked the X next to the composite term and was able to unmap the application term (i.e., the button turned gray and now says "map to existing bedes term"). I shouldn't be able to unmap someone else's application terms, even if they are public. Public means other people can view it, but not edit it.

[TravisWalterLBNL]

Same issue when logged in as one user and being able to unmap a different user's application term.

[TravisWalterLBNL]

Downgraded from high priority to medium because the application term doesn't actually get unmapped. Initally, it appears as though it's unmapped, but if you go back to the list of application terms and refresh the page, the mapping is intact. So, this is really just a display issue. The desired behavior would be that the mapped term is grayed out (indicating it can't be modified, as with the application term name, description, etc.), and for nothing to happen if the user clicks the X by the mapped term name.