Provide more clarity on which specific validation failed

[grzuy]

No description provided.

[grzuy]

As per @brauliomartinezlm recommendation in #80 (comment) we may want to consider raising exceptions for each specific invalid condition in the responses.

[grzuy]

I am thinking we can:

• define new methods #verify which raise on any verification error on the responses.
• keep current #valid? methods, which:
  • just calls #verify and catches verification errors and continues to expose the same behavior to the user returning true or false.