Update README.md
Add a travis CI configuration file.
remove extra whitelisted branches.
Make maven build only fail at the end, so extensions that fail won't short-circuit other independent extensions.
remove latest-javadoc, javadoc & individual api-diff dirs since they're stored in gh-pages now.
remove latest-javadoc, javadoc & individual api-diff dirs since they're stored in gh-pages now.
Merge branch 'master' of github.com:google/guice
Merge pull request #812 from cgruber/travis

Add an initial travis CI configuration file.