beta: update job for cxserver

Cxserver is a nodejs app maintained by the l10n team and its deployment
is very similiar to the Parsoid one. Being too lazy to create a
template, I merely copy pasted the parsoid update job and adjusted it.

Might want to refactor later on.

Creates job beta-cxserver-update-eqiad

Change-Id: I4ea3262fbfd9516b3e4432b8a5f167ff149fdcf5