save two times was no bug:
1st save: DocPath in relay task
2nd save: Docpath in read out Exchange

	modified:   lib/receive.js
	modified:   lib/utils.js
	modified:   lib/worker.js
	modified:   package.json
	modified:   test/utils.test.js
generic http request function
	modified:   doc/collections.js.md
	new file:   doc/request.js.md
	modified:   doc/worker.js.md
	new file:   lib/request.js
	modified:   lib/worker.js