Allow a single note to be applied to all selected alerts. Also updated node-sass version.

[headphonejames]

Previously, the only way to apply a note to an alert is by going to the alert detail view and then adding a note using the button. This PR allows a note to be applied to all alerts that are selected in the alert list view.

When an alert is selected in the alert list view, a new "notes" button appears. When that button is pressed, a text input line appears under the table header. Any text submitted in that text input will become notes applied to all alerts selected in the alert list view.

This PR also updates node-sass version and removes package-lock.json to see if it fixes build issues on netlify.

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