Clean up requires

Rather than calculating paths ourselves, trust the load path to include
reek's files, and, during the spec run, reek's spec files. In the
gemspec, the load path needs to be set explicitely.
Remove superfluous initializers

The removed initializers basically just called super. The default
parameter is always correctly infered using the base class' code.
Clean up whitespace and formatting
Remove Array monkey patch
Submit reek to its own default set of smells
Merge pull request #143 from troessner/cleanup

- Clean up require statements, make them trust the load path
- Remove superfluous initializers in smell detector classes
- Clean up some whitespace and formatting issues
- Remove the Array#intersection monkey patch
- Remove xp.reek