Add issue template

Author: ivogabe

issue_template.md

@@ -0,0 +1,34 @@
+<!--
+Before submitting an issue, check that the following questions can be answered with yes:
+
+- Is this related to gulp-typescript, and not to TypeScript?
+- Is the behavior of gulp-typescript different than the behavior of tsc?
+- There was no similar issue already opened? (Please don't bump old closed issues)
+
+If you can answer all these questions with yes, add a description of your issue here and fill in the related sections below.
+-->
+
+**Expected behavior:**
+
+**Actual behavior:**
+
+**Your gulpfile:**
+
+*Include your gulpfile, or only the related task (with `ts.createProject`).*
+```javascript
+
+```
+
+**tsconfig.json**
+
+*Include your tsconfig, if related to this issue.*
+```json
+
+```
+
+**Code**
+
+*Include your TypeScript code, if necessary.*
+```typescript
+
+```