Add logging around recursive discovery and hashing

[chadhietala]

This was asked for in broccolijs/broccoli-filter#28

[chadhietala]

This should probably be replayed against the latest.

[stefanpenner]

we are using heimdall now:

hash-for-dep/index.js

Line 63 in 35b3140

var h = heimdall.start(heimdallNodeOptions, HashForDepSchema);