deploy: Install eNovance GPG key in deploy server

We provide python-pip and python-crypto in eNovance repository (with a
newer version than wheezy/trusty), the install of this package cause an
error (unauthenticated package if the eNovance key isn't present).

Please see
https://os-ci-admin.ring.enovance.com/view/eDeploy/job/eDeploy-Build-All-OpenStack-Debian/473/consoleFull
or maybe we should use the TRUSTED =1 ?