Add WES support

Launching MacOs App from the console:

1. Set AIRFLOW_HOME environment variable to use a custom location for Airflow home directory
2. Run configuration script (do it every time you change AIRFLOW_HOME)
   cwl-airflow.app/Contents/MacOS/init
   Script will run airflow initdb, update airflow.cfg, copy DAGs and create required connections
3. Run scheduler
   cwl-airflow.app/Contents/MacOS/airflow scheduler
4. Run API server (use -h to see additional parameters)
   cwl-airflow.app/Contents/MacOS/apiserver

Launching MacOs App from a Finder:
NOTE: the default location for AIRFLOW_HOME will be used ~/airflow

1. Double click on cwl-airflow.app
   Script will create three services in ~/Library/LaunchAgents
com.biowardrobe.airflow-scheduler.plist
com.biowardrobe.airflow-webserver.plist
com.biowardrobe.airflow-apiserver.plist
2. Use Load and Unload buttons to start and stop services.
3. If cwl-airflow.app is moved to another location, make sure to manually remove abovementioned plist files