Localization strings and added default pot and pt_BR files

Hi, Brad.

Firstly, congrats for that plugin. It's a great time saver for database migration tasks.

I was going to only translate it to Brazilian Portuguese, but it was not language friendly. So I took the liberty to change all printed texts inside it, including in script.js.

I hope it can help you to accept other languages support.

Cordially,
Rafael Funchal