Version 0.3.0 with refactored source and many new features

- Structure and versioning
  - Switched to 3 part version number
  - Moved version number to separate file
  - Python package structure with setup.py
  - Added requirements.txt (reqs. are in setup.py!)
  - Code split in Locker module and Locker "binary"
  - Locker module contains Container and Project classes
- Logging and output
  - Improved and unified log output
  - Print port/netfilter rules in status
  - Added color as attribute to containers for consistent output
  - Nicer status output thanks to prettytable
- Port forwarding / netfilter rules
  - Support of tcp and udp ports directives (default: tcp)
  - Add/remove netfilter (ports) rules on start/stop automatically
  - Modification of netfilter rules can be optionally skipped
- Misc.
  - Extended example YAML file to cover all cases
  - Added support to set the FQDN in the container
  - Extended .gitignore
  - Added check if YAML configuration file exists
  - Updated README to reflect recent changes
  - Added several items to the To-Do / wish list