Improve environments
Remove duplicated warning opion on test
Remove trailing blank lines
Clarify to use ASCII-8bit from Ruby 2.0 too
Improve file tree
ByeBye Ruby 1.9.2 :)
Update YARD syntax
Improve documents
Bump version to 0.0.2

Most APIs are not changed.
But renamed a file to extend String `lib/abb/ext -> lib/abb/core_ext`
That needs to bump version :(