Readd ping release generation tasks.

GitHub releases just look nicer than plain tags.
Use the new build env on Travis

more ram, more cpu, better network, improve vm start times

http://docs.travis-ci.com/user/workers/container-based-infrastructure/

more docs coming soon
Updaté Travis build

- Add Composer vendor folder to travis cache.
- Add GitHub OAuth token to reduce risk of hitting API limit.
- Remove —prefer-source when installing dependencies. This should no longer be necessary as Composer falls back on source if diet fails.