devDeps/test: ganache-core->ganache-cli

The supplied version has a broken dependency specification for
frozeman/WebSocket-Node and therefore does not install at all.
ganache-core has itself been superceded by ganache-cli and later
ganacher, which both provide compatible interfaces.

ganache-cli is in fact also deprecated, but the replacement ganache
depends on a version of leveldown not compatible with legacy nodejs
versions. A future change should take the next step.

This has been tested down to nodejs v8.17.0.

Author: legobeat