Update unetbootin so it doesn't depend on Qt4 which will be removed soon (boo#1179613)

- Update to revision 681
- Change selectable openSUSE versions only to supported versions:
Leap_15.1, Leap_15.2, Tumbleweed, Factory
- Rebase patches.
- Run spec-cleaner

- Add Qt5 port patches from https://github.com/unetbootin/unetbootin/pull/137:
* 0001-rought-Qt5-port.patch
* 0002-comment-out-all-sources-that-require-FTP-LIST.patch
* 0003-fix-distrolst.cpp.patch
* 0004-don-t-wait-until-the-file-is-downloaded-fully-before.patch
- Refresh unetbootin-suse.patch:
* add Leap 15.0 and 15.1
* Update the download URLs and the distro description
- Refresh unetbootin-locate-usb-devices.diff
- Run spec-cleaner

- update to revision 661

- require p7zip-full for TW as 7z binary needed by unetbootin was
moved to this package (see bsc#899627 for more details about
this change)

- update to revision 657