The action creator for removing custom devices calls the one for remove device
association directly, which skips the step of also messaging the manager.
I've made the simplest change to fix just this issue, which moves the message
sending into the action creator for this one case. Bug 1332754 will apply the
same approach to other messages (they aren't causing issues yet since they are
not called from other action creators in the same way).
MozReview-Commit-ID: AICcT2vG1wl
This change brings the following improvements to RDM:
* Page state is preserved when toggling in and out of RDM
* Session history is no longer manipulated, so the tool UI won't end up in the
tab's back-forward page list.
Known issues to be fixed later:
* The browser UI is not hooked up to the viewport browser
* Restarting the browser with the tool open shows a confused, empty RDM
MozReview-Commit-ID: Fb6QRv6LYow
