Issue template (#455)

* Adding ISSUE_TEMPLATE

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,20 @@
+<!--
+If this is a bug report please fill out the template below.
+
+If this is a feature request please describe the behavior that you'd like to see.
+-->
+
+**Environment**:
+
+  - CTFd Version/Commit:
+  - Operating System:
+  - Web Browser and Version:
+
+**What happened?**
+
+**What did you expect to happen?**
+
+**How to reproduce your issue**
+
+**Any associated stack traces or error logs**
+