Unify password handling and add password.enc option to pass encrypted passwords.

There is an unused 'password' option; make it an alias to 'sshpassword' and
set password even without ssh enabled (it's also used for rescue system).

Add 'password.enc' and 'sshpassword.enc' to allow passing passwords in
encrypted form.
explicitly set CURLOPT_IPRESOLVE to debug/workaround resolve issues (bnc #889981)
Merge pull request #18 from openSUSE/sw_0006

Sw 0006