Check the bearer token before talk client requests

[eatyourgreens]

Share the beforeEveryRequest method between the API client and the Talk client.

Fixes zooniverse/Panoptes-Front-End#4179

[camallen]

LGTM - though to me it was not obvious this is coupled to the underlying json-api-client behaviour to get called

[eatyourgreens]

I only realised it existed by reading the Panoptes client code.

panoptes-javascript-client/lib/api-client.js

Lines 10 to 13 in fddfedc

	beforeEveryRequest: function() {
	var auth = require('./auth');
	return auth.checkBearerToken();
	},