FIX: Validate poll arguments. (#6740)

* FIX: Validate number poll.
* FEATURE: Poll's min can be 0.
* FIX: Fix URL to user profile.

plugins/poll/assets/javascripts/widgets/discourse-poll.js.es6

@@ -8,6 +8,7 @@ import evenRound from "discourse/plugins/poll/lib/even-round";
 import { avatarFor } from "discourse/widgets/post";
 import round from "discourse/lib/round";
 import { relativeAge } from "discourse/lib/formatter";
+import { userPath } from "discourse/lib/url";
 
 function optionHtml(option) {
   return new RawHtml({ html: `<span>${option.html}</span>` });
@@ -143,6 +144,7 @@ createWidget("discourse-poll-voters", {
       return h("li", [
         avatarFor("tiny", {
           username: user.username,
+          url: userPath(user.username),
           template: user.avatar_template
         }),
         " "
@@ -560,8 +562,8 @@ export default createWidget("discourse-poll", {
 
   min() {
     let min = parseInt(this.attrs.poll.get("min"), 10);
-    if (isNaN(min) || min < 1) {
-      min = 1;
+    if (isNaN(min) || min < 0) {
+      min = 0;
     }
     return min;
   },