Revert "updated queue dependency to v2.2.0"

This reverts commit 394fff482f1ca35f59119e8874b78e44dfc8ae0d.

Conflicts:
	index.js
Revert "added tests for start and stop"

This reverts commit d49c0fca7cae5708503f04a48af64c3e1857b304.

Conflicts:
	index.js
	test/chain.js
fix(errors): message should clearly indicates that there is a callstack