Confirm dialog box before the deletion of a tag. (Bug number - 1077669) 

Confirm dialog box pops up when clicked on "delete".

added confirm_delete function to the tagmanager.js file which controls the default based on the response.
Have a look at the rest of the file. You'll notice a pattern.
* Functions have camelCase style
* Variables have under_score style
* Indentation is 4 spaces 
* There's a space between the `)` and the `{`.