Get a rectangle area of cloudiness data 

- integrate to https://www.weatherapi.com/pricing.aspx

- input: 
  - upper-left corner of the rectangle area in decimal degrees: +32.30642, -122.61458
  - bottom-right corner
  - resolution in meter

- output: array of data points
```
[
{"lat":32.23423, "lon":-123.21234, "cloud":60},
...
]
```