trufflesuite/ganache v2.1.6 on GitHub

Release Highlights

Pins ethereumjs-wallet to v0.6.0, to work around a problem with this dependency which broke HD Wallet support.
Switches project to use npm-shrinkwrap.json instead of package-lock.json so that projects which depend on ganache-core are getting the same dependency versions we test against.
Fixes a bug wherein the provider engine wasn't being stopped when the ganache-core was provider was stopped, which makes ganache-core more useful in contexts where it might need to be spun up multiple times in a single process.