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).
Merge pull request #101 from enovance/python-crypto

deploy: Install eNovance GPG key in deploy server