add more status updates

templates/emails/printing.body.txt

@@ -0,0 +1,17 @@
+Hi,
+
+Great news -- your hamprint submission "{{ submission.slug }}" is on the
+printer right now. The operator has started the job and the first layer
+is going down.
+
+    Codename : {{ submission.slug }}
+    Status   : Printing
+
+We'll send one more email when it finishes, so you know when to come
+pick it up. No action needed in the meantime.
+
+You can also follow along here:
+    {{ detail_url }}
+
+— hamprint
+{{ site_url }}