Fix scraper

[isaacmg]

Our scraper currently depends on: covidatlas/li#619 . We may have to switch to JHU or another data source if this doesn't work.
@efawe

[isaacmg]

@antonpolishko

[antonpolishko]

Data crawler utils should be also refactored since they are broken when you install corona-ts as a package, specifically line 9 in data_crawler.py, should not depend on relative path to cache timeseries.csv