Add Bulk Partner URL editing tool

[blackjackkent]

Expected Behavior

As a user, if my partner changes their blog URL, I want to be able to update their URL for all threads where I am tracking them in the WatchedShortname field.

Current Behavior

Currently, to change a WatchedShortname value on multiple threads, a user must edit each thread manually.

Possible Solution

We should be able to implement a tool for this in the "Tools" section of the app with a very similar interface to the existing Tools->Manage Tags section. The user should be able to enter the shortname of a partner who's URL has changed (ideally with autocomplete based on all the current WatchedShortname properties of threads in their account) and bulk update that property on all associated threads to a new value.

This will require updates to both this project and http://www.github.com/blackjackkent/RPThreadTrackerV3.BackEnd