Config feature
feature #291 Config feature (nicktacular)

This PR was squashed before being merged into the 0.4.x-dev branch (closes #291).

Discussion
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Config feature

Regarding #288, these fixes have been added:

 * Config::addCustomFixer returns $this to be fluent
 * Fix command does a sanity check on the config file and bails if there's something wrong with it (i.e. doesn't return an instance of Config)

Commits
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65048f8 Config feature
refactored some code
fixed typo