Fixed IPv6 Validation according to https://gist.github.com/cpetschnig/294476
Fixed ERROR: 'rake/rdoctask' is obsolete and no longer supported. Use 'rdoc/task' (available in RDoc 2.4.2+) instead.
/ipaddress/Rakefile:47:in `<top (required)>'
Fixed + Added Test Cases
Update README.rdoc

Small fix
Updates Rakefile from obsolete rake/rdoctask to rdoc/task
Merge branch 'brona-master' into develop
Add RUBY_VERSION conditional test for UTF-8 encoded strings in ruby >= 2.0
Change obsolete rake/rdoctask with rdoc/task
Merge branch 'develop', fixes #32
Update CHANGELOG
Add ipv6 test on 'dd', fixes #34