Provide hash function transformer/option

[alexisvisco]

I think it will be a good idea to provide same input same output in order to preserve consistency across a database.

You could imagine having a parameter :

- name: email
  transformer_name: email
  hash: true

With that parameter and that input [email protected] this will produce something like ddaf35a193617abacc417349ae20413112e6fa4e89a97ea20a9eeee64b55d39a2192992a274fc1a836ba3c23a3feebbd454d4423643ce80e2a9ac94fa54ca49f@gmail.com with a sha512 hash function (using md5 will be faster but less secure)

[evoxmusic]

Hi, good suggestion. I think it can even be a new type of Email Transformer. HashEmailTransformer. Feel free to open a PR if you want :)