A recent commit (I29c73355a85112840b57f93b39a9eeda421875e6) updated the
epel element to rely on wget, but wget is not always installed. Since
wget is used in pre-install.d, we must install it in that phase.
Change-Id: Iad2a9c4f0081835a1aa78e6fd2f721f6afd44dc2