title: Convert any encoding to UTF 8 in Go
body: <p>I'm downloading messages via IMAP. Next I'm adding parsed message into MongoDB. And I've a problem, because MongoDB support only UTF 8. And I wanna convert any encoding to UTF 8. Codes are various. How can I convert each string to UTF 8?</p>
  
  <p>I know, that I can convert to binary, but I have to have normal text, because I have to searching phrases in database. Unless, can I searching normal text in binary?</p>