Configurable Geonames download URL

[tpedelose]

Takes care of #239

The download function can now take a custom url - defined in the config file as imports.geonames.sourceURL from which to download a file. If sourceURL is undefined or an empty string the code defaults to the official Geonames dumps. The defined url can be a "template literal" format where ${countryCode} will be evaluated with the given countryCode.

Other changes (let me know if these should be broken out to other PRs or tossed entirely):

• moved bin/download_data.js main code out to lib/task/download.js to match template of other files
• renamed bin/download_data.js to bin/downloadData.js to match camelCase format of other files

[orangejulius]

Hey @Tiranno,
Thanks for this PR. It looks great. My only suggestion would be to avoid the use of eval(). We don't really need that much flexibility here, and eval() opens up all sorts of possible issues.

Having the config variable be a string which is a URL prefix which is concatenated with the country code to generate the full URL should be enough.

[tpedelose]

So you're thinking something like 'http://example.com/' + countryCode + '.zip'?

[orangejulius]

Yup, that would be perfect

[orangejulius]

Just tested and this works perfectly. thanks!!