Remove checking config value with empty() (only supported in PHP 5.5+)
Merge pull request #11 from zoltanpeto/master

Remove checking config value with empty() (only supported in PHP 5.5+)
Refactored cache method to a CacheTrait file
Renamed Codex to CodexRepositoryFlat and extracted CodexRepositoryInterface
Added initial CodexRepositoryGit implementation
Fixed issues with CodexRepositoryGit linking
Brought code into spec with upstream master
CodexRepositoryGit now uses branches instead of tags
Each branch is now checked out
Added CacheTrait usage to Git driver