Clean up rake tasks

* Remove metric_fu tasks
  - metric_fu now has its own runner
  - metric_fu is not part of the bundle, so these tasks were not
    available when run with `bundle exec`
  - loading these tasks takes an insanely long time
* Delay loading yaml dependency until needed
* Delay requiring Reek sniffer until needed
* Remove dependency declarations for obsolete tasks
* Remove unused Rakefile constants
* Remove needless dependencies
* Do not manipulate the load path: The 'lib' directory is already added
  to the load path by 'bundler/gem_tasks'.
* Remove needless square brackets
* Expect config/ to exist: its contents is in git, and it should not be
  removed by `rake clobber`.
Make rake test:quality work

The pattern option does not seem to work if it does not start with
'spec'.
Merge pull request #296 from troessner/fix-test-quality-task

Make rake test:quality work
Merge pull request #293 from troessner/clean-up-rake

Clean up cruft from rake tasks
Add auto-generated RubuCop TODO list
Exclude samples from RuboCop analysis

This already fixes a great number of offenses
Auto-correct spacing offenses
Auto-correct trailing white space and blank lines
Auto-correct hash rockets
Fix TrailingComma offense
Autocorrect SpaceInsideHashLiteralBraces offenses
Fix StringConversionInInterpolation offense
Allow small arrays of words with quotes
Excule tmp/ from RuboCop analysis
Allow single-line method definitions
Always use raise to signal exceptions
Autocorrect percent literal offenses
Autocorrect SpecialGlobalVars offenses
Fix Semicolon offenses
Fix IndentHash offense