Adds galaxy favicon

Fixes #8

Author: bbengfort

static/favicon.png

@@ -12,6 +12,9 @@
   <meta name="description" content="Machine learning in data space web demo.">
 
   <!-- shortcut icon -->
+  <link rel="shortcut icon" href="{{ url_for('static', filename='favicon.png') }}">
+  <link rel="icon" type="image/png" href="{{ url_for('static', filename='img/galaxy-192.png') }}" sizes="192x192">
+  <link rel="apple-touch-icon" sizes="180x180" href="{{ url_for('static', filename='img/galaxy-180.png') }}">
 
   <!-- stylesheets -->
   <link href="https://stackpath.bootstrapcdn.com/bootswatch/4.3.1/flatly/bootstrap.min.css" rel="stylesheet"