Added Travis integration

- Better `lib` vs `lib64` check (e.g. Debian/Ubuntu uses `lib` also for 64-bit)
- Use Travis CI (see e.g. https://travis-ci.org/lslezak/libyui/builds/33472844 for example build)

*Note: Enable Travis support for `libyui/libyui` repo <b>before</b> merging this PR so the master branch is checked by Travis after merging.*
Just in case this breaks IBS (Never Happens(TM)), this should be documented in `ChangeLog` (the local name of .changes, wtf): "Detect lib64 in a Debian compatible way, for Travis CI."