Maven3

Update our poms to fix all the warnings that maven3 gives off.

Changes made:

- Remove the blueflood-udp dependency from blueflood-all
- Add version to maven-javadoc-plugin
- Added MainClass config to manifest in uberjar. (allows you to start blueflod like: java -jar blueflood-uberjar.jar) (not a requirement for maven3, but I thought it was neat and probably useful to java newbies).
- Marked testing dependencies in blueflood-http as optional. (also not necessary for maven3, but should help make the uberjar a bit smaller).
- Got rid of blueflood.version.

About blueflood.version:
maven3 gave warnings about this, and said that support for the version being an expression may be dropped in future versions of maven. So to shut maven up, I used the same pattern that dropwizard uses: https://github.com/dropwizard/dropwizard/blob/master/dropwizard-configuration/pom.xml

We can use the `versions` maven plugin to update the versions in all our poms. Used like so: `mvn versions:set -DnewVersion=2.0.1-SNAPSHOT`.  That updates the parent pom and all child poms as well.