System Console: Email notification content setting (#7122)

* PLT-7195: Added new config option, new license feature, and config UI to system console. Still need to implement behaviour change in email batching code

* PLT-7195: Modified batch emails to respect email notification content type setting

* PLT-7195: Tweaking the colours a bit

* PLT-7195: Added support for email notification content type setting in immediate (non-batched) notification messages. Attempted to clean up the code somewhat. Unit tests coming in a future commit

* PLT-7195: Added unit tests for non-batched emails

* Checked license when applying email content settings

* Changed return type of getFormattedPostTime

templates/post_batched_post_generic.html

@@ -0,0 +1,37 @@
+{{define "post_batched_post_generic"}}
+
+<style type="text/css">
+    @media screen and (max-width: 480px){
+        a[class="post_btn"] {
+            float: none !important;
+        }
+    }
+</style>
+
+<table style="border-top: 1px solid #ddd; padding: 20px 0; width: 100%">
+    <tr>
+        <td style="text-align: left">
+            <span style="font-size: 16px; font-weight: bold; color: #555; margin: 0 0 5px; display: inline-block;" >
+                {{.Props.ChannelName}}
+            </span>
+            <span style="font-weight: bold; white-space: nowrap; color: #555;">
+                @{{.Props.SenderName}}
+            </span>
+            <br/>
+            <div style="margin: 5px 0 0;">
+                <span style="color: #AAA; font-size: 12px; margin-left: 2px;">
+                    {{.Props.Date}}
+                </span>
+            </div>
+        </td>
+    </tr>
+    <tr>
+        <td colspan=2>
+            <a class="post_btn" href="{{.Props.PostLink}}" style="font-size: 13px; background: #2389D7; display: inline-block; border-radius: 2px; color: #fff; padding: 6px 0; width: 120px; text-decoration: none; float:left; text-align: center; margin: 15px 0 5px;">
+                {{.Props.Button}}
+            </a>
+        </td>
+    </tr>
+</table>
+
+{{end}}