Email/Query sort by hasKeyword

= WHY

With the new specifications as an user i want to be able to sort the emails by the presence of a given keyword

`hasKeyword - This value MUST be considered true if the Email has the keyword given as an additional keyword property on the Comparator object, or false otherwise.
`

Here is the query to display first the emails containing the 'james' keyword.

[[ "Email/query",{
  "accountId": "ue150411c",
  "sort" : {
      "property": "hasKeyword",
      "keyword": "james",
      "isAscending": true
}
}, "0" ]]

= HOW

• accept the 'hasKeyword' value in the 'property' field of the sort field of the request.

= DOD

• write an integration test demonstrating the sorting of the result by 'hasKeyword' in both ascending and descending order