Rubocop: enable style check, Style/TrailingWhitespace
rubocop: remove trailing whitespaces
add version badge for displaying README.md
add Travis-CI build status badge
add gem guard-rubocop
create Guardfile
rubocop: add exclude rule, Guardfile
Merge pull request #5 from gouf/rm_trailing_whitespace

Remove trailing whitespace by rubocop
Merge pull request #6 from gouf/version_badge

add version badge for displaying README.md
Merge pull request #7 from gouf/travis_ci_badge

add Travis-CI build status badge
Merge pull request #8 from gouf/guard_rubocop

guard-rubocop