Eclipse/Aether migration

Mostly dependency and import changes, plus some refactoring due to changes in the Aether API/SPI

https://issues.sonatype.org/browse/NEXUS-6776
Just in case, Eclipse Aether is equipped with JSR-330 annos, has Sisu index files and a Guice module, cf. http://git.eclipse.org/c/aether/aether-demo.git/tree/aether-demo-snippets/src/main/java/org/eclipse/aether/examples/guice/DemoAetherModule.java