Show generic suggested tweet on present dropdown use

[martinstabe]

When using the presets in dropdown, two things don't behave as expected:

• The suggested Tweet is not displayed, causing the histrogram to drop too low in the div. Suggest we display a generic tweet here.

• The selected area is not highlighted on the histogram. I think we decided this was not fixable by forcing a postcode to be selected, though.

[maxharlow]

This was updated to show some text where the tweet would be:

Highlighting an area on the histogram indeed not possible as we only have postcode data

[aendra-rininsland]

Fixed in e7a20d30a31cc0beed424c4bd5d7998fb6763eeb.