Add tests for new config

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
New config class

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Updated config sample (synch with new Config)

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Fixes to follow new Config

- replace get(key) and ['key'] calls by dotted notation
- removed defaults from the codebase (as they now all live in the config)
- tweak existence tests
- simplified calls to load() when possible
- assume proper typage

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Return config objects even from environment

+ enhanced typage tests

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Type from environment properly (like Config)

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Config update + privileges drop (fix #440)

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Fix travis bustage by removing redis hard dependency in common

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Update registry core as we break drivers

Docker-DCO-1.1-Signed-off-by: Mangled Deutz <olivier@webitup.fr> (github: dmp42)
Registry now depends on core>=2.0

Docker-DCO-1.1-Signed-off-by: Olivier Gambier <olivier@docker.com> (github: dmp42)
Merge pull request #444 from dotcloud/config-enhance

Config rehaul