add mulit-file upload form to /danger/snapshots.html template.

This commit is just the front-end. The back-end, at time of this commit has not
been implemented.

The form allows users to upload 'Snapshots' to the website  -- with the
intention of then restoring the website from that back-up.

templates/danger/snapshots.html

@@ -34,6 +34,47 @@
 	</button>
     </form>
 
+    <div class="be-storage-section-upload">
+        <form action="/danger/upload-snapshot"
+	      method="POST"
+	      enctype="multipart/form-data">
+            <input required
+	           type="hidden"
+	           name="AUTHENTICITY-TOKEN"
+	           value="{{token}}">
+            <input required
+	           type="file"
+	           name="SNAPSHOT-FILES"
+	           multiple>
+            <button class="be-gui-button-no-text"
+	            title="Click to upload Snapshots"
+	            type="submit">
+	        <img alt="Upload to Snapshots"
+	             src="/images/icons/up-arrow.png">
+            </button>
+        </form>        
+    </div>
+
+            <p>
+                <strong>Note:</strong>
+                
+                If you see a 'successful upload' alert message, after using the
+                Multi-File Upload box above, you might not see any Snapshots
+                appear down below. This is because you can upload multiple files
+                at once.
+
+                <strong>
+                    The website will ignore any files which have the same name
+                    as any of the Snapshots below or are not a .zip file.
+                </strong>
+
+                The system is relaying how the upload <em>went</em> and not the
+                validity of the files you uploaded. In other words, the website
+                recognised the files you uploaded and their file-types; It just
+                ignored the 'irrelevant' ones.
+                
+            </p>
+
     <div class="be-section-entries">
     {% for item in snapshots %}
     <div class="be-section-entry">