Does not appear to play well with PhantomJS

When running tests I get a hard failure that appears to point to something in the markdown editor:

```
PhantomJS 2.1.1 (Mac OS X 0.0.0) ERROR
  SyntaxError: Unexpected token 'const'
  at webpack:///~/v-markdown-editor/src/index.js:4:0 <- index.js:252953
```

Version 1.0.7.

Please advise.