Use git clone --recursive thatrepo

NOTE: using the ssh protocol for each submodule for interacting more conveniently with the GitHub remote.

travis.yml is an example for a working Travis configuration, just copy it into your project as .travis.yml. What this will do is:

• Do a matrix build using Oracle's JDK7 and 8 (available at Travis out of the box) combined with Maven 3.0.5 and Maven 3.3.3 by the help of the the Takari Maven Wrapper.
• Downloading the Maven versions is done on the fly so the git repositories are not "polluted" with wrapper code.
• Running test-compile dependency:go-offline during the Travis install phase will do most of the downloading stuff before running the interesting stuff in the Travis script phase, i.e. clean verify.