Improve maven/github release workflow

[baltzell]

• populate github release artifacts (the build tarball) from CI, rather than manually uploading (Automatically publish build tarball to release assets #450)
• automate versioning and -SNAPSHOT naming management with proper maven (build!: various cleanups #515)
• replace deploy shell script with maven
• use a top-level maven config for repeated stuff

[baltzell]

closed by #515 and #536

[c-dilks]

replace deploy shell script with maven

deploy-coatjava.sh basically just does mvn deploy with some extra stuff, so it uses a Maven deployment plugin now; I did not use an SSH URL in the deployment plugin config in coat-libs/pom.xml, since we also need to scp a tarball anyway, so I think this is good enough for now.

use a top-level maven config for repeated stuff

#632 made some progress on this, not sure how much duplication is left

[baltzell]

mostly done:)