fix possible XSS in view issue page

templates/repo/issue/view_content.tmpl

@@ -124,7 +124,7 @@
 
 	  		<div class="detail">
 	  			<span class="octicon octicon-git-commit"></span>
-	  			<span class="text grey">{{.Content | Safe}}</span>
+	  			<span class="text grey">{{.Content | Str2html}}</span>
 	  		</div>
   		</div>
 			{{end}}