use "@var_x" rather than deprecated "var_x" in (inline) templates

Puppet 3.2 adds a deprecation warning about using e.g. '<%= variable %>' in templates, advising us to switch to '<%= @variable %>' (as the former will be removed someday).

This patch switches several (107) instances of inline templates using '<%= [var_x.sort.collect..' to '<%= [@var_x.sort.collect..' so they no longer trigger the warning.

perl -pi -e 's{(?<=\Q"["+\E)(?=var)}{@}g' manifests/*.pp manifests/*/*.pp

cc @phrawzty