runChain, pure and error
Revert "runChain, pure and error"

This reverts commit 300aae25589a9077b98ca8479b9e8c19d436563e.
HttpError class
update README
export HttpError class
log errors
add bf.check for param validation
remove check tests from chain file
playing around with our own sequence function
allow using `next obj` instead of `next null, obj` when in a `.then` callback
few extra methods
fix error in .then
middleware function
use req instead of fields for middleware
better sequence
export middleware
typo
allow deferred function to be specified for bf.chain
Object type
reasons for validation errors