feat: support <route> custom block

[ktsn]

DEPRECATED: <route-meta> is deprecated in favor of <route>

fix #67
fix #144
fix ktsn/vue-auto-routing#21

It supports <route> custom block which allows users to overwrite route record.

Example users.vue:

<route>
{
  "name": "UserPage",
  "props": true
}
</route>

The following route record will be generated:

routes: [
  {
    name: "UserPage",
    props: true,
    path: '/users',
    component: Users
  }
]

Note that it does not allow to overwrite path and component option.