Fix creating a mail share with a password

When a mail share was created with a password the given password was not
hashed, so it was not possible to open the share with that password.
Moreover, if passwords were enforced the given password was ignored and
a new one was set (although in this case it was hashed so it worked as
expected). Now the given password is properly hashed and not overriden.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>