Add session discovery and template support

examples/session.template.yml

@@ -0,0 +1,12 @@
+session_id: "{{ session_id }}"
+campaign: sample-campaign
+date: ""
+title: ""
+inputs:
+  audio_dir: ./audio
+  # Optional S3 input alternative. Do not configure with audio_dir/audio_files.
+  # audio_s3:
+  #   prefix: "audio/{{ session_id }}/"
+  speakers_file: ./speakers.yml
+  autocorrect_file: ./autocorrect.yml
+  glossary_file: ./glossary.yml