fix WorldBank API

[alxndrkalinin]

We need to fix WordBank API and add few more options for dataset. So far I was using 20.000 cells as a soft limit for dataset size to allow clustering/bootstrapping – so number of record to retrieve can be calculated as 20.000/#cols. However, user can get more records and then SOCRAT will suggest to uniformly subsample rows.

Subtasks:

• [x] fix Education spending
• [x] fix Out-of-school children rate
• [ ] add few more datasets (up to 10-15)
• [x] fix styling of controls: inputs, dropdowns (we're using FlatUI)

[chartotu19]

@alxndrkalinin So if the user imports more than 2000/column, app should limit the number of rows to satisfy - rows*columns == 2000. Did I get that right? Also, Is there any mathematical technique for sub sampling or just Math.random?

[alxndrkalinin]

@chartotu19, sorry, typo, it's 20.000

I was talking about 20.000/#cols as a way to figure out what would be a default value for how many rows by default to request from WorldBank. E.g. if Education Spending category has 10 columns, than you show 2.000 rows as a default. However it's okay to let user to request more (up to max allowed by API).

Also, subsampling is already implemented – e.g., if you try loading Knee Pain dataset it'll suggest subsampling

[chartotu19]

the fix for missing header is pushed now. PR is ready to be merged feature-wise