Support "contains" and "overlap" filtering (v2)

[lucas-bremond]

This PR adds support for the contains and overlap filters of Django.

This is basically extending #1070 (written by @tcleonard).

---

Contains:

query {
  # Returns Events that have `music` AND `sport` tags.
  events(tags_Contains: ["music", "sport"]) {
    edges {
      node {
        name
        tags
      }
    }
  }
}

Overlap:

query {
  # Returns Events that have `music` OR `sport` tags.
  events(tags_Overlap: ["music", "sport"]) {
    edges {
      node {
        name
        tags
      }
    }
  }
}

---

Note: this also applies the project setup fix from #1087 to the v2 branch.

[zbyte64]

Stellar work. Any chance you can create a v3 as well? If not that's cool too, I can take care of that if needed.

[lucas-bremond]

Stellar work. Any chance you can create a v3 as well? If not that's cool too, I can take care of that if needed.

@zbyte64 Here you go! #1101

[tcleonard]

There is actually an issue with this PR I think. I think it breaks the name_Contains kind of filter (normal contains Django filter on string fields).
I'm looking for a way to fix this... will submit a PR asap.