Support launching Mimic easily from Node.js

[john-twigg-ck]

Is your feature request related to a problem? Please describe.
I want to use Mimic in unit tests in node.js

Something like

describe('Unit test', () => {
    before(async() => {
        mimic.start("features.mimic")
    })
    it('Test Feature', (done) => {
        //test things that also make thrift calls
    })

    after(async () => {
        mimic.shutdown()
    })
})

Describe the solution you'd like
I'd like a single line entry for loading a mimic file and starting up the service stubs.

Describe alternatives you've considered
Running a shell script in parallel, but this wont work for Circle CI.

Additional context