Update all packages for security issues

[krepflap]

I updated all the packages with npm audit fix to fix the security issues in dependent package versions. Things seem not to break.

• gulpfile had to be modified a bit to support 4.x syntax
• fixed two errors that showed up while running gulp (in open.js and use.js, both undefined vars)
• re-added a sample test case (from master branch) so the command npm run test doesn't fail spectacularly, and this paves the way for adding test cases
• the package upgrade in ranvier-websocket is a major one, things seem fine but more testing might be needed there

Is this useful ? I have some spare time to work on other things too if there is interest.

[shawncplus]

Closing this only because I'm removing gulp/mocha/sinon/chai from the project since they're unushed. Gulp is only being used to call eslint which is easy enough to call on its own and there are currently no tests. I'll re-add them when we actually have tests.