nmbug.js: Fill in the tag-fetching portion of nmbug.show
nmbug.js: Fill in the tag-fetching portion of nmbug.show

Ask nmhive for the tags associated with the given Message-ID.

I've also used bind [1] so that the nmbug.show callback get's called
with this pointing to the nmbug object.

[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind

wking/nmhive,wking/nmhive