Config && dry-run work

- now sports a config class that can do all sort of magic / preparation / legacy handling
- new command line flag -d (--dry) that just tries to load the config and exit (will catch a number of config errors, although not all) - need extra work
- new http / https configuration syntax that allows binding individually on any number of ips / port, with specific certificates
- fixes #4 (but not SNI yet)
- fixes #10
- on the road to fix #122
Fix factory tests now that array is the only supported argument
Better config + unit tests
Priv dropping
Stop overriding 0 values.
Fix test config back to sane values
Updated config to follow new syntax
Make linter happy
Fix syntax...
Fix typos and default user to www-data
Migrate TODO file to bug tracker before it bitrots (see #122 #123)
Slight README cleanup. Also feature Airfield (fixes #14)

Conflicts:
	README.md
Linter
Remove default www-data group (will fallback from user value anyhow).
Updated configuration documentation. Also fixes #116.

Conflicts:
	README.md
Merge pull request #143 from dotcloud/0.4.rebase

0.4.rebase