unit tests in single file (fixes #223)

[paulpflug]

adds the possibility to add unit tests to the vue file - to keep together what belongs together

This is rather large. A short overview of the content:

• removed peer deps to remove errors when not using babel (see Could we please drop peerDependencies? vueify#81)
• includes improved changes from pad results with whitespace - re #190 #230 + missing unit test for style sourcemap
• bumped all deps
• moved source map test to use coffee-loader instead of babel-loader (which won't work as expected and failing the test)
• moved mocha tests to karma where possible to show of the new feature

missing: documentation - I'm willing to provide these if this gets accepted.

example for testing a unmounted component:

<script>
module.exports = {
  data () {
    return {
      msg: 'Hello from Component A!'
    }
  }
}
</script>
<template>
  <h2 class="red">{{msg}}</h2>
</template>

<style>
comp-a h2 {
  color: #f00;
}
</style>

<script test>
var module = window.vueTestComp
var styles = window.document.querySelectorAll('style')
var style = styles[styles.length-1].textContent
describe("vue-loader", function () {
  it('basic', function () {
    expect(module.template).to.contain('<h2 class="red">{{msg}}</h2>')
    expect(module.data().msg).to.contain('Hello from Component A!')
    expect(style).to.contain('comp-a h2 {\n  color: #f00;\n}')
  })
})
</script>

example for testing a mounted component:

<template>
  <h2 class="red">{{msg}}</h2>
</template>

<script>
module.exports = {
  data () {
    return {
      msg: 'Hello from Component A!'
    }
  }
}
</script>

<script test="karma">
var module = window.vueTestComp
describe("vue-loader", function () {
  it('karma', function () {
    expect(module.$el).to.exist
    expect(module.msg).to.contain('Hello from Component A!')
  })
  after(function () {
    module.$destroy(true)
  })
})
</script>

[yyx990803]

Hey, thanks for the PR! Ideally we should split changes into separate, smaller PRs each addressing one problem so they are easier to review and merge. Big PRs like this involve too many moving parts to be merged in one go.

[paulpflug]

splitted in 3 PR