Add CSV Downloader

Is a generic Csv Downloader for all indicators specified in the config
file (the url pattern matches only WHO queries)
End WHO importer

Add CSVReader
Add methods needed to generate observations
Refactor WHOImporter

Make it more extensible (no code needed to add new indicators)
Delete some unused exceptions
Adapt importer to the new model
Add historical mode
Improve support to historical data

Now the init values are automatically updated by the importer
Improve errors control

Clean unused code
Add available translations in document
Update translations in indicators
Add support for easy command execution
Add trasnlated organization descriptions
Unify names
Update configuration.ini

Update logo url
Send file paths to modelToXML but not creating zip
Send adecuate import_type to m2x
Merge remote-tracking branch 'origin/develop-importerWHO' into develop