tapicero uses curl in a way that leaks the password in the process list

Tapicero is running this curl command to watch the _changes file in couch, and unfortunately it is doing so in a way that leaks the password in the process list.

It should be using the netrc file for this.

This was fixed in the whitebox tests in #5445 (closed)

(from redmine: created on 2015-02-03, closed on 2015-02-05, blocks #6708 (closed))