Add minimum_should_match clause to or/nor filters to really filter by should clause

[cewald]

If you use an or/nor filter it would be applied without a specific minimum_should_match value. This could lead into wrong results as it is not adding a reducing filter, just a or/nor that doesn't affect the results.

Example:

Consider the following final query:

{
  "query": {
    "bool": {
      "filter": {
        "bool": {
          "must": [
            {
              "terms": {
                "color": [ "blue" ]
              }
            }
          ],
          "should": [
            {
              "terms": {
                "size": [ 11 ]
              }
            },
            {
              "terms": {
                "is_in_sale": [ 1 ]
              }
            }
          ]
        }
      }
    }
  }
}

We wan't to load products that have the color "blue" and products that are "in sale" or have size "1"
– BUT without minimum_should_match we just ask for a definitiv color and the should filter must not be fulfilled as minimum_should_match is 0 by default.

[cewald]

@Fifciu @gibkigonzo I've updated to the latest master branch – are any updated/changes necessary?