Add GitHub issue template (#725)

Author: benvinegar

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,11 @@
+**Do you want to request a *feature* or report a *bug*?**
+
+(If this is a *usage question*, please **do not post it here**—post it on [forum.sentry.io](https://forum.sentry.io) instead. If this is not a “feature” or a “bug”, or the phrase “How do I...?” applies, then it's probably a usage question.)
+
+**What is the current behavior?**
+
+If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar.
+
+**What is the expected behavior?**
+
+Which versions of Raven.js, and which browser and OS are affected by this issue? Did this work in previous versions of Raven.js? Are you using the CDN (http://ravenjs.com)? Are you using [hosted Sentry](https://sentry.io) or on-premises? If on-premises, which version (e.g. 8.7.0)?