Add issue template

The issue template is a guide to help the contributors report issues.

ISSUE_TEMPLATE.md

@@ -0,0 +1,19 @@
+## Precheck
+
+- Do not use the issues tracker for help or support, try Stack Overflow.
+- For bugs, do a quick search and make sure the bug has not yet been reported
+- Finally, be nice and have fun!
+
+## Environment
+
+- Ruby **[version]**
+- Rails **[version]**
+- Devise **[version]**
+
+## Current behavior
+
+Include code samples, errors, steps to reproduce the error and stacktraces if appropriate.
+
+Will be even more helpful if you provide a sample application or a test case that reproduces the error.
+
+## Expected behavior