Prep for pushing to maven central.

Here is how it works:

1. We push snapshots to the sonatype repository willy nilly, whenever we want.
1. When things are stable, we stage a release.  A version can be re-staged if problems are found.
1. When that is really stable, you publish a release.  Sonatype eventually picks this up and pushes it to maven central.

We're not ready for 3 yet, but if you specify the sonatype nexus repo as a repository, you can use BF snapshots.  This will be good enough for most.

Some things changed along the way:

1. to avoid a dependency on our handcrafted 1.0.8 cassandra maven plugin, I changed the dependency to 1.1.0. 
1. this means we get rid of the local repository. woo!!!!
1. get rid of the gelf jar for sake of tidiness.
1. build source and javadoc jars.
1. avoid uploading `blueflood-all` since it is so big.
1. point to the sonatype parent pom.