Add features, and clean up code

* Added a ‘debug’ mode for the entrypoint script.
* Added a ‘debug’ mode for postfix.
* Structured and cleaned up the entrypoint script.
Update README.md
Fix CMD
Fix default volumes

The directory '/var/log/' was missing as a default VOLUME.
Update README.md

Updated fig.yml example with a better example.
Remove quickstart example

Removed quickstart example and provided a link to a gist instead.
Remove /var/log/ volume
Update README.md
Add IP_ADDR environement variable

Added the IP_ADDR environment variable in order for supervisorctl to listen on that address.
Add supervisorctl support
Add port 9001

Added port 9001 for the listening port of supervisorctl.
Merge branch 'feature/log' into develop
Change environment variable name
Add SUPERVISOR_PASSWORD environment variable
Update README.md
Fix SMTPS protocol

Added SASL authentication via dovecot.
Release Version 1.2

* Added supervisorctl support for starting and stopping postfix, and viewing 'maillog'
* Updated README with better layout and wording.
* Fixed SASL authentication for SMTPS.
Merge branch 'release/v1.2'

Conflicts:
	README.md
	app/entrypoint