2.1.0 Jest support

The main purpose of this release was support for Jest framework

Features

• ui: adds support for jest
• interface: exports get and def functions from every dialect file. So, now it's possible to write tests as this:

const { def, subject } = require('bdd-lazy-var/global')

describe('Suite', () => {
  def('suite', () => new Suite())

  it('has parent', () => {
    expect($suite).to.have.property('parent')
  })
})