Fix update_version.sh script for 0.4
Fix update_version.sh script for 0.4

* Update location of securedrop group_vars file
* Update version in testinfra vars

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