"Follow" button in the "Processing ticket" view

Hi.

Currently a person can specify if the person wants to get notification via e-mail by clicking on the ticket -> ticket tab -> click on the small envelope icon -> e-mail followup -> Yes/No -> Save. This hides the funcionality very well.

I propose to have a simple "Follow/Following" button on the "Processing ticket" page with the followin logic.

1. Currently not following the ticket. Label is "Follow". After pressing this button, it will change to "Following". Person is added to the "watcher" list
2. Currently following. Label is "Following". After pressing this button, it will change to "Follow". Person remains on watcher list, but e-mail notifications for this specific ticket are disabled for this specific person.