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 to mention it, if all you guys are doing with Wagon is to use the HTTP impl, you might want to try the aether-transport-http on occasion. It uses httpclient+jcl-over-slf4j and might save you some exclusions and intermediate dependencies.