Count the active contacts that match the filter with the given ID

Example

GET https://api.maileon.com/1.0/contacts/filter/{contactFilterId}/count/active
Content-type: application/vnd.maileon.api+xml
Accept: application/vnd.maileon.api+xml; charset=utf-8
Authorization: [XXX]

Status: 200 OK
Content-Type: application/vnd.maileon.api+xml;charset=utf-8

<count>2</count>