DAG Creation to Enable Non-Injection Analyses

Changed the list of topic_prefix based on whether Injection Channel Names are specified.

Changed the way inspiral.py handles Injection & Non-Injection Layers. datasource options, arguments & kafka_server have been indented left. The channel-name Option was removed from arguments.extend() and added in the subsequent lines. The next steps add appropriate channel names to their respective layers based on whether the jobs are Injection or Non-Injection. It only attaches inj_layer if nodes in it are present.

This was tested using config_small_bbh.yml by commenting out inj-channel-names for both cases. The online_inspiral_dag.dag was checked to confirm only jobs specified (gstlal_inspiral and gstlal_inspiral_inj) were being created. The scald_metric_collector_leader jobs were checked to confirm only necessary topics were populated.

The repository can be found here: /ligo/home/ligo.org/shomik.adhicary/small-online-analysis/run/small-bbh