Add Travis testing

Thanks @geerlingguy!
Do not do sysctl stuff on travis runs

Adds the redis_travis_ci variable, which won't run the sysctl stuff
when the role is run via Travis CI. They appear to be blocking these
changes.
Add status reporting for Debian init script

For #14, but also a requirement for Travis idempotency check in #19
Add Redis smoke test
Add Travis build icon thingy
Merge pull request #19 from DavidWittman/travis

Add Travis testing