Switch to Travis for CI and production deployment

 - Add .travis.yml configuration

 - Update Gradle `deploy` task with awareness about Travis CI build
   environment. Only go through with production deployments if on master
   and Travis's "secure environment variables" are present (they are not
   in the case of pull requests from forks). See
   http://docs.travis-ci.com/user/encryption-keys
   http://docs.travis-ci.com/user/build-configuration/#Secure-environment-variables
   http://www.gradle.org/docs/current/userguide/userguide_single.html#sec:gradle_properties_and_system_properties

 - Eliminate `ci-deploy.sh` entirely in favor of the above

 - Send HipChat notifications to the Sagan room

 - Set TERM=dumb in order to produce clean Gradle console output in the
   Travis web UI. See
   http://stackoverflow.com/questions/17942819/how-can-i-get-clean-gradle-output-on-travis-ci

 - Disable git submodule processing by Travis build, as it was causing
   problems. It's unnecessary in any case, as it's just the wiki. See
   http://docs.travis-ci.com/user/build-configuration/#Git-Submodules

 - Update README build status badge to reflect Travis CI vs. Bamboo

 See https://travis-ci.org/spring-io/sagan
Merge pull request #331 from spring-io/travis