Add devtools
Get most of the metrics passing
Add config/mutant.yml
Add missing specs for Yardstick::Config
Add missing specs for Yardstick::Document
Add missing specs for Yardstick::MeasurementSet
Add missing specs for Yardstick::OrderedSet
Add missing specs for Yardstick::Processor

* Make Yardstick::Processor simpler - Delegates work to parser and
DocumentSet.
* Add Yardstick::Parser - Talks directly with YARD, returns set of
documents.
* Add Yardstick::DocumentSet - Wrapper for documents.
Add missing specs for Yardstick::Rule and Yardstick::Rules
Add missing specs for Yardstick::DocumentSet
Add missing specs for Yardstick::Rake tasks
Add missing specs for Yardstick::Parser
Add missing specs for Yardstick::ReportOutput
Add missing specs for Yardstick
Fix Yardstick::Processor#process spec
Increase unit_test_timeout a bit

Travis rbx-18mode failed with:
  Unit test took 0.10097199999999999 but max allowed is 0.1
Increase unit_test_timeout a bit

Travis jruby-19mode failed with:
  Unit test took 0.253 but max allowed is 0.2
Ensure summary length is validated correctly
Remove spec/support/config_alias.rb
Fix coding style