Merge pull request #9 from adriaanm/travis

Enable Travis CI
Remove trace macro. Too unstable.

Also, it was duplicated in scala/scala.
This one seems to have been unused.
Add sonatype snapshots repo.

So that we can PR validate against Scala snapshots.
Merge pull request #10 from adriaanm/excise-trace

Remove trace macro. Too unstable.
Proudly display Travis CI status
Update README.md
Only validate against 2.11.0-SNAPSHOT
Automate release: settings for dependency versions.

Enable building against Scala 2.11.0-SNAPSHOT.

Disable `-Xfatal-warnings` to make PR validation less painful.
TODO: Re-enable for travis / nightlies.

TODO: Bump to Scala 2.11.0-M7, Scalacheck 1.11.0 once they're out.