pom changes required for distribution on the sonatype nexus snapshot repo
build sources-jar and javadoc-jar during package phase.
Remove local repositories and set the cassaandra-maven-plugin version to be 1.1.0-1.

The reason is that it is hard/impossible to get these dependencies up on maven central, and ends up making the project less "pure" in maven terms.

See https://docs.sonatype.org/display/Repository/Sonatype+OSS+Maven+Repository+Usage+Guide#SonatypeOSSMavenRepositoryUsageGuide-6.CentralSyncRequirement (search for 'discourage').
include some sonatype stuff in the pom.
do not include blueflood-all by default (we don't want to upload it during a deploy)
Merge pull request #77 from gdusbabek/prep_pom_for_mvn_central

Prep for pushing to maven central.