chore: add an issue template.

Author: hansl

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,55 @@
+> Select one of the following:
+>
+> I am filing a bug.
+>
+> > In this case you need the following information:
+>
+> ---------------------------------------------------------------
+1. OS. Windows 7, 8 or 10. Linux (which distribution). Mac OSX (Yosemite? El Capitan?)
+2. Versions. Please run `ng --version`. If there's nothing outputted, please
+   run in a Terminal: 
+
+        node --version
+        npm --version
+        npm info angular-cli
+   And paste the result here.
+3. Repro steps. Tell us exactly what you did and how you came to the failure. 
+   If you can give us steps from the moment you created an empty application,
+   even better! Please try to be as descriptive as you can; this will avoid
+   unnecessary back and forth. Was this an app that wasn't created using the
+   CLI? What change did you do on your code? etc.
+4. The log given by the failure. Normally this include a stack trace and some
+   more information.
+5. Mention any other details that might be useful.
+> ---------------------------------------------------------------
+> > Thanks! We'll be in touch soon.
+>
+> I am filing a feature request.
+>
+> Unfortunately, for now, although we accept proposals, it will be probably be
+> deferred. It's not that we don't want to hear you, it's that we're focusing
+> on the beta release and as such we want to keep things a bit tidier than it
+> will be once this is out in the open.
+>
+> We're not closed to good ideas, we simply have a limited amount of bandwidth.
+> There's only 24 hours per day.
+>
+> ---------------------------------------------------------------
+>
+> I want customer support / I don't know how to do X.
+>
+> This is unfortunately not the right place. Please join the discussion on
+> gitter, Stack Overflow or twitter and don't be afraid to post your
+> questions there. A FAQ will be created with those and it will help answer
+> questions other people might have as well.
+>
+> ---------------------------------------------------------------
+>
+> I want to help!
+>
+> Please read our contributing guidelines;
+> https://github.com/angular/angular-cli/blob/master/CONTRIBUTING.md
+>
+> If you really want to be part of the crew and start cracking,
+> try to contact us on gitter. We're never really far and we might have
+> something just for you!