Remove autotools generated files, eliminate hardcoded DEFBASE, add .travis.yml

- Other autotools-based projects I see in Github don't check in all the code-generated junk. They usually include an autogen.sh  script for running autoconf to generate that stuff. So, removed all those ugly files. Instead, interested parties should DIY by invoking autogen.sh
- Got rid of DEFBASE by using @abs_top_builddir@ macro in autoconf.
- Added a .travis.yml file for Travis-CI builds... can't try it at the moment since Travis is under a DDoS attack, but it'd be nice to be able to ensure you don't break the Linux build when you commit from Mac.