travis: build with bobtail dependencies

Adds .travis.yml that installs bobtail debian packages and other
dependencies, and then builds lua-rados. The setup currently does not
run any tests.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
readme: add markdown readme file

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>