Fix rubocop violations
Merge pull request #53 from vid-io/fix/rubocop-violations

Fix rubocop violations
Fix Ruby 1.8 support
Fix rubocop warning

Now `expect { ... }.to raise_error(...)` is "good" for both Ruby 1.8 and rubocop
strict rules of coding styles :D
Merge pull request #55 from vid-io/fix/ruby-18-support

Fix Ruby 1.8 support