Generate complete URL that is to be included in the Email.
S3 has a global bucket namespace so just using GTFAR_S3_BUCKET is not enough.

Add code to see if a bucket exists with prefix GTFAR_S3_BUCKET. If yes, use it else create_bucket GTFAR_S3_BUCKET-<UUID>
Add method to get the bucket name being used.
Remove GTFAR_S3_BUCKET from default.py as it will be computed at runtime.
Set GTFAR_S3_BUCKET name if S3 will be used by the application.
Introduce GTFAR_S3_BUCKET_PREFIX constant in S3Utils class.
Generate S3 specific sections only if S3_BUCKET_NAME is present.
Initial code for more granular status tracking.