Create taskgraph out of all tasks before filtering.
Fixes #6
Minor cleanup in network module
Adjust README to point at the documentation.
Remove outdated CONTRIBUTING.md
Introduce format_command. Fixes #7
Use --arch in euca-bundle-image. Fixes #23
Move AKI info into JSON file. Fixes #13
Also introduced config_get() to retrieve a specific value from
these JSON files. Comments are now supported in those files as well
PEP8 compliance
Move virtio module list into "system". Fixes #5
Make 'packages' optional
Translate release names into codenames. Fixes #15
Use `type' to check if command available. Fixes #11
Split up RequiredCommands task.
The requirements are now located in the appropriate modules
Rely on $PATH to resolve commands. Fixes #12
Check if current user is root. Fixes #20
Zerofree can be installed as a Debian package
Show alternate message when package string for host_dependencies starts with http:// or https://