Tidy up the ‘Activity’ table

This table had a lot of columns, which meant that some of them became
very narrow, wrapping the text awkwardly.

This commit groups some of the data into a chunk, which occupies the
first column.

app/assets/stylesheets/components/table.scss

@@ -77,6 +77,14 @@
     width: 15px;
   }
 
+  p {
+    margin: 0 0 5px 0;
+
+    a {
+      text-decoration: none;
+    }
+  }
+
 }
 
 .table-field-heading {