Dev/7 polygon import scripts

[fzeiser]

Summary: Added script to download Kartverkt's data. [originally #10, see there for more info, but I cant reopen it after a forced push to update my email address]

Script will download the data from kartverkt's API. Currently it will just dump the data. (edit: manual download necessary)

TBD:

• [ ] Get (last) modification date of the resource (edit: not possible, see #10)
• [ ] Importing hook to database.
• [x] Add other data, like TED -> different script?

Related Issue: https://github.com/metno/MetAlert-Search/issues/7

Reviewer checklist:

• [ ] The headers of all files contain a reference to the repository license
• [ ] 100% test coverage of new code
• [ ] All tests are passing
• [ ] All names (e.g., files, classes, functions, variables) are explicit
• [ ] Documentation (as docstrings) is complete and understandable

[fzeiser]

Status:

• Changed kartverket source to manual download, as the automatic download via the API does not provide enough metadata:

  Modification date / validity date of the features (polygons) is not available from the API. Thus, if one uses it, one would anyhow manually need to go in and check, what their current source is. Older versions cannot be downloaded via the API, e.g. the Fylke boundaries from 2010 (arb. choice). Therefore, I think a manual download and completion of the metadata as read from the website less error-prone. ). The lack of metadata retrieval was confirmed in the response of a mail I wrote to them. See #10

• quality check of TED import: See #10

• Importing hook to our database: Waiting for Data class or import API.

[fzeiser]

@vkbo: flake8's W503 and W504 are in conflict with each other. We have to ignore one of them; I'd suggest ignoring W503.

(W503 line break before binary operator)