JavaScript for subscribing should be refactored for reuse

I won't make this one for this cycle, but will catch it first of next cycle.

Why is this bug marked as affecting launchpad-code?

rockstar is wanting to use this JavaScript when it's refactored for branch subscriptions and asked me to file this bug against launchpad-code, too.

Thanks! Triaging appropriately (I hope).

I've started work on this, see the linked branch, which was committed in devel in r8791. There are now Subscriber and Subscription JavaScript objects for abstracting out those two concepts. There is more work to be done before this bug is finished, but the work is underway at least.

Given all that we have to do for the 3.0 UI push, I'm marking this low priority and considering my inline subscribing work done. There is enough there in the code that exists now and with the recent addition of Subscriber and Subscription objects in lib/canonical/launchpad/javascript/bugs/subscriber.js that I hope Paul (and others) can find the work useful in building similar inline subscribing tools.

I've landed a branch that starts this cleanup. However, I think the lazr-js sprint will be the best time to really evaluate how we're going to go about cleaning this up entirely, since there are differences in branch and bug subscriptions -- Nothing huge, but enough to be annoying.

The subscription stuff has been widgetified for branches, and after talking with Deryck at UDS, it sounds like this will be able to be re-used once bug subscriptions gain state. It's pluggable enough that one could hook in a custom flow (which is what branch subscriptions do). I think that means it's fixed for code at least.