Updates class-validator and class-transformer to latest versions

[thomaux]

This PR updates class-validator and class-transformer to their latest versions, allowing projects that depend on class-transformer-validator, to update to the latest versions of the peer dependencies.

Changes:

• The latest class-validator no longer lists @types/validator as a runtime dependency, that's why it's been added to the list of dependencies here.
• The 0.5.0 version of class-transformer replaces the usage of the word Class in methods to Instance. Example: plainToClass is renamed to plainToInstance.

[NoNameProvided]

Just chiming in, those functions while deprecated were removed accidentally, 0.5.1 re-added them. However, it's still a good idea to use the new name.

[thomaux]

Thanks for the update @NoNameProvided, upgrading to 0.5.1 does indeed work with the existing version of class-transformer-validator