Create functionality to fetch articles include all given tags

[b-m-f]

At the moment, when supplying tags to get_artciles in wordpress_api.py these tags are either or.

Such that when using tags=[1,2,3], all articles with either tag 1,2 or 3 will be fetched.

We should add functionality to fetch only articles that have all given tags.

For example a with_tags=[1,2,3] such that only articles that have all tags will be returned.

[carkod]

This should be pretty easy to achieve wtih https://stackoverflow.com/a/44666295/2454059. But I wonder if we need this functionality at this point