[meta] New issue template to redirect template-specific issues

[chrisvfritz]

I noticed that many issues here have nothing to do with vue-cli itself, but rather with the templates that I'm guessing many simply aren't aware of. I'm wondering is an ISSUE_TEMPLATE.md might help - perhaps something like the following?

<!--

IMPORTANT: Did the `vue init` command *itself* result in an error?

  -> NO: If the files for a project template were correctly created, but did 
         not work out-of-the-box as you expected, please open an issue for the
         appropriate template at github.com/vuejs-templates

  -> YES: Open an issue here. Please include the exact command you used, 
          what you expected to happen, and what happened instead.

-->

[yyx990803]

Absolutely! PR welcome :)

[chrisvfritz]

Ha, just beat me to it!