Patch /etc/hosts to include hostname pointer.

Not having this entry breaks the JDK unfortunately.

Related to travis-ci/travis-ci#1723 and travis-ci/travis-ci#1178.
Use tee -a
Don't log hostname patch.
Redirect patching of hostname to /dev/null.
Merge pull request #184 from travis-ci/mm-set-local-hostname

Patch /etc/hosts to include hostname pointer.