use showRangeSelector for dygraph

[gizzygizmo]

In file /app/templates/device_dashboard.html adding 'showRangeSelector: true," to line 520ish where "g2 = new Dygraph(" will enable the range selector which I believe is easier to navigate.

Opening a beer log that is multiple days is easier to navigate with the range selector slider than using zoom/selector.

[gizzygizmo]

g2 = new Dygraph(
    document.getElementById("graphdiv2"),
    {#  TODO - Something here if active beer isn't set #}
    "{{ beer_file_url }}", // path to CSV file
    {
{#        labels: [{{ column_headers|safe }}],#}
        labelsDiv: document.getElementById('label-div'), // Technically, this is unused because of legend:never
        legend: "never",
        axisLabelFontSize: 14,
        displayAnnotations: true,
        showLabelsOnHighlight: true,
        hideOverlayOnMouseOut: false,
        showRangeSelector: true,
        // TODO - Test this with gravity data
{% if beer.model_version > 1 %}
...