readme: update build instructions for Linux

Update the actual needed package names for
Debian-based systems, don't advertise in-tree build.

Signed-off-by: Steve Markgraf <steve@steve-m.de>
add configuration file for Travis CI

Signed-off-by: Steve Markgraf <steve@steve-m.de>
Merge pull request #3 from steve-m/master

update readme and add support for Travis continuous integration service