Add def clean doc. Add Belarus example.
2.1.1, Fix for case where country code is already in number when normalizing a specific country.
Fix Belgian numbers (closes #130).
Add reference for Belgium.
Added performance tools (not working on Rubinius yet).
Improve performance checks.
Speed up normalizing.

(Running bundle exec rspec takes 0.24s)
.
Add Rubinius performance tool.
Add plausible? to performance script.
Small clarification.
Merge branch 'master' into fix-problem-with-brazilian-numbers-with-ddd-19