etherpad to use own cert, not wildcard

Replace the wildcard cert with one specific for etherpad.wikimedia.org.
Also the install certifcate call isn't located in any etherpad manifest
calls, and was relying on another service to have installed, fixed to
install its own certificate.

Change-Id: I9c4b5df89d8ebc01f36adfd3cedb38da07dbeb03
RT:6591
Merge "etherpad to use own cert, not wildcard" into production