Fix parsing of cli option --fixer

Use fixers from config also if no or empty --fixer option on cli is
used.
merged branch Danez/patch-3 (PR #221)

This PR was merged into the master branch.

Discussion
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Fixers from config not used when no --fixer supplied

Use fixers from config also if no or empty --fixer option on cli is used.
This is broken since ee3cef18b1f016576a8631ee0930aad3a2268939

Commits
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42d9eb0 Fix parsing of cli option --fixer