To make this possible, the following changes were made:
* Use `Task` to start the load process
* Create `ets` table before start the async task
* This is needed to keep the tables alive after the task process exits
* Adjust the application to start the `Growth.Indicators.Load` task
1. calculate age in days, weeks, and months
2. calculate body mass index for metric and english unities
3. calculate z-score for a given measurement and box-cox parameters (l,
m, s)
4. calculate centile score for a given measurement and box-cox
parameters
Initial implementation to fetch growth indicators from WHO.
For now, the system merges the measurements for each gender and age
group in a single `csv` file.
The final solution should do this, saving a `dets` file.
