Fix: plan details photo missing

[timwangmusic]

Description

A highly recurring issue on production is Image of unknown format : image/png. It is frustrating for users seeing a blank image when swiping through the trip details page carousel.

Solution

• Decode image with png decoder if the content format is png.
• Update photo reference in database so we do not need to make place details search request in the future for the same place. Removing the stale places is infeasible since the place may be linked to user saved plans.
• Added a new places endpoint so admins can observe photo reference update easier.

Testing

• [x] Integration testing on Heroku staging

Checks

• [x] Have you removed commented code?
• [x] Have you used gofmt to format your code?

[rwangsc18]

Thanks @timwangmusic for fixing this bug! Great work!