Elasticsearch package isn't in the Ubuntu repo

[waynegemmell]

Elasticsearch doesn't exist in Bionic so installation fails when determining version.

- Rendering SLS 'base:elasticsearch.plugins' failed: Jinja variable dict object has no element 0
  /var/tmp/.salt_1a862b_salt/running_data/var/cache/salt/minion/files/base/elasticsearch/settings.sls(20):
  ---
  [...]
    {% if pillar_major_version %}
      {% set major_version = pillar_major_version %}
    {% else %}
      {% set pkg_version = salt['pkg.version'](elasticsearch_map.pkg) %}
      {% if pkg_version %}
        {% set major_version = pkg_version[0] | int %}    <======================
      {% else %}
        {% set major_version = False %}
      {% endif %}
    {% endif %}
  {% endif %}