Updated versions of various Maven plugins in POMs and tidied up differences

- Updated the Maven plugin version numbers to latest usable releases
- Tidied up references to repositories for release/deploy builds
- Consistent setting of build properties for java version etc.
Agreed; folk get an error from Eclipse without this. The quick fix for storing it in local eclipse metadata is nicer, but even nicer would be for the user to not have to worry about it so I vote for leaving it in.