Account for Ruby's multi-line regular expressions

[jsl]

• Ruby uses multi-line regular expressions by default
• Change Transform classes to match beginning and end of String
• Add tests for Transform classes
• More details: http://guides.rubyonrails.org/security.html#regular-expressions

[kachick]

https://github.com/kachick/safe_yaml/commit/6bc4839b71ddf360c377deb90edbbb4b7ee5b104 https://github.com/kachick/safe_yaml/commit/78ee2a1454cb87ed6270b52eb99a672231d38a71

I have tried it too, but then used \z. Is \Z more better than \z in this case?

[dtao]

Nice, thanks @jsl and @kachick! (Just read the article from the Rails docs—learned something new!)