Add text overrides for band checklist

Requested via Slack.

magprime/templates/guest_checklist/band_bio_deadline.html

@@ -0,0 +1,13 @@
+{% extends "guest_checklist/bio_deadline.html" %}
+
+{% block deadline_text %}
+{% if guest.bio_status %}
+    You have already provided us with your information, but you can use the link above to update it.
+    {% if not guest.bio.uploaded_pic %}
+    We encourage you to upload a picture (which you have NOT yet done) so that we can
+    include it on our website.
+    {% endif %}
+{% else %}
+    Use the link above to provide us with the information needed to promote your presence at Super MAGFest via Social Media.
+{% endif %}
+{% endblock %}

magprime/templates/guest_checklist/band_travel_plans_deadline.html

@@ -0,0 +1,11 @@
+{% extends "guest_checklist/travel_plans_deadline.html" %}
+
+{% block deadline_text %}
+{% if guest.travel_plans_status %}
+    You have already told us how you will be traveling to {{ c.EVENT_NAME }}, but you can use the link above to update your
+    preferences.
+{% else %}
+    Use the link above to provide travel details so that our liaison team can coordinate with you on providing anything that 
+    you may need to arrive at Super MAGFest.
+{% endif %}
+{% endblock %}