Added .travis.yml to tell travis-ci about the project.
Can travis-ci handle the GWT project?
Nope.  Travis-ci doesn't seem to like the GWT project any more than Cloudbees did.  Hmm.
Update status icon in README to refer to travis-ci.
Merge pull request #39 from DavidWhitlock/travis-ci

Use travis-ci for continuous integration.
Merge branches 'java-8' and 'master' of github.com:DavidWhitlock/PortlandStateJava into java-8
Use Java 8 when building with travis-ci.