Integrated logging

The set_prefixed_format() function updates the formatter and sets
prefix for every logged message. This prefix, cluster_id, will act
as a filter during search/debugging.

MyStreamIO will be use to redirect stdout of fabric.run/sudo(). The
write() method has been updated to log directly using flask logger.

Signed-off-by: Shashank Sahni <shredder12@gmail.com>