[Add] add valine comment system

_config.yml

@@ -132,6 +132,12 @@ comments:
     admin: # GitHub repo owner and collaborators, only these guys can initialize GitHub issues, IT IS A LIST.
       # - your GitHub Id
 
+  ## Valine
+  # please refer to https://valine.js.org/en/index.html for more info.
+  custom:
+    API_ID     : # LeanCloud App id
+    API_Key    : # LeanCloud App key
+    placeholder: Just Go Go. # Prompt information
 
 ## => Pageview
 ##############################

_includes/comments-providers/custom.html

@@ -0,0 +1,22 @@
+
+{%- if page.key and
+    site.comments.custom.API_ID and
+    site.comments.custom.API_Key and
+    site.comments.custom.placeholder -%}
+
+    <div id="vcomments"></div>
+    <!--Leancloud 操作库:-->
+    <script src="//cdn1.lncld.net/static/js/3.0.4/av-min.js"></script>
+    <!--Valine 的核心代码库:-->
+    <script src='//unpkg.com/valine/dist/Valine.min.js'></script>
+    <script>
+        new Valine({
+            el: '#vcomments',
+            appId: '{{ site.comments.custom.API_ID }}',
+            appKey: '{{ site.comments.custom.API_Key }}',
+            verify: true,
+            placeholder: '{{ site.comments.custom.placeholder }}'
+        })
+    </script>
+
+{%- endif -%}