Broken encoding on email reply (BB-3267)

Sent response thru Gmail has broken encoding.

//
Nebude to úplně tak triviální, protože nevím
//

is saved as

//
Nebude to =C3=BApln=C4=9B tak trivi=C3=A1ln=C3=AD, proto=C5=BEe nev=C3=ADm,=
//

Happened here: https://bitbucket.org/jlkcz/ijacek/issue/7/na-log-symlink-se-nejde-dostat-p-es-ftpko (private repository)