Ganache-cli: Support IPC endpoint

[axic]

Some tools (i.e. Mist, Solidity tests, etc.) have switched to use IPC instead of the HTTP-RPC.

Would it be hard adding IPC support? (That would need to replace the http server when the option is turned on. Ideally listening on both an IPC file and HTTP would be nice.)

[tcoulter]

Quick google makes it look promising: https://www.npmjs.com/package/node-ipc

I have no idea how IPC works, but this would be a good feature.

[axic]

@tcoulter well the term IPC is overused, but what these clients really mean is a Unix socket or a Windows pipe. node-ipc seems to support that.

[boorac]

Definitely would love to see this happen

[miguelmota]

Looking forward to IPC support

[axic]

I had IPC support implemented in https://github.com/trufflesuite/ganache-cli/pull/261, but it was closed after half a year of not merging it :)