Create BE API for Resource Statistics

[raresraf]

raresraf/metricsUI#8

Mocks:

statistics = {
        'requests_24': 12345,
        'requests_all': 12345,
        'time_24': 567,
        'time_all': 890,
        'average_time_24': 1.23,
        'average_time_all': 1.2345,
        'sd_time_24': 1,
        'sd_time_all': 2,
        'size_24': 111567,
        'size_all': 111890,
        'average_size_24': 1111.23,
        'average_size_all': 1111.2345,
        'sd_size_24': 1111,
        'sd_size_all': 1112
    }
    resp = jsonify(statistics)
    resp.status_code = 200
    return resp