Downgrades Ansible to 1.8.4 for testinfra requirements
Downgrades Ansible to 1.8.4 for testinfra requirements

We're currently requiring an older version of Ansible due to the version
available via apt in Tails, which uses the Jessie Stable repos, being
1.7.2. Unfortunately 1.7.2 doesn't install cleanly via virtualenv,
but 1.8.4 does, so let's use that as a close comparison.

We're working on bumping to a modern (2.2.1+) version of Ansible in the
0.4 release of SecureDrop. In the meantime, we should be careful to test
with older versions.

ehartsuyker/securedrop,conorsch/securedrop,heartsucker/securedrop,conorsch/securedrop,micahflee/securedrop,ageis/securedrop,conorsch/securedrop,heartsucker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,ehartsuyker/securedrop,heartsucker/securedrop,micahflee/securedrop,ehartsuyker/securedrop,conorsch/securedrop,ehartsuyker/securedrop,ageis/securedrop,micahflee/securedrop,conorsch/securedrop,garrettr/securedrop,heartsucker/securedrop,garrettr/securedrop,ageis/securedrop,garrettr/securedrop,heartsucker/securedrop,ageis/securedrop,micahflee/securedrop,garrettr/securedrop