Replace mapper-attachment plugin by Tika

If we want to have a finer control of JSon documents we generate, we need to remove the attachment type (mapper-attachment-plugin that is) and replace it with Tika.

It will allow to support features like `"store-origin": false` which basically won't require to  encode in Base64 the content but only will generate json values for extracted content.

We need probably here to keep the original format of generated Json documents for bw compatibility.

Closes #38.