clients incorrectly requiring auth parameter for sensors source

[pedritom-amzn]

problem: the auth parameter is optional for the sensors api:

delphi-epidata/src/server/api.php

Lines 1309 to 1314 in c48af8f

	if(require_all($data, array('names', 'locations', 'epiweeks'))) {
	if(!array_key_exists('auth', $_REQUEST)) {
	$auth_tokens_presented = array();
	} else {
	$auth_tokens_presented = extract_values($_REQUEST['auth'], 'str');
	}

however, the clients are all incorrectly requiring the auth parameter to access sensors, e.g.:

delphi-epidata/src/client/delphi_epidata.py

Lines 459 to 463 in c48af8f

	def sensors(auth, names, locations, epiweeks):
	"""Fetch Delphi's digital surveillance sensors."""
	# Check parameters
	if auth is None or names is None or locations is None or epiweeks is None:
	raise Exception('`auth`, `names`, `locations`, and `epiweeks` are all required')

impact: customers of the clients will be incorrectly restricted from using the sensors source without auth.

proposal: make auth optional for sensors in the clients.