[atlas] Minor changes in the probe archive API

Dear colleagues, We made some changes to the probe archives API. The changes relate to the use of another storage back-end. In addition to the "date" URL argument, which returns the all probes dump for the given date, the new version enables ranges of dates to be specified for all or selected probes. The example below will return dumps for probes 1, 5, 81, 82, 83 for dates in the range [2018-01-03, 2018-01-06): https://atlas.ripe.net/api/v2/probes/archive?/api/v2/probes/archive?date__gte=2018-01-03&date__lt=2018-01-06&probe=1,5,81-83 Best regards RIPE Atlas Team