Fix #27 – support Maven 3.1+

Maven has switched to Eclipse Aether in 3.1 and it’s sadly incompatible with Sonatype Aether. Plugins directly using Sonatype Aether simply doesn’t work on Maven 3.1+ (the current Maven version is 3.2.1). It seems that there’s no way how to support pre and post 3.1 versions with the same codebase. :(

IMHO it’s better to throw away compatibility with Maven 3.x and older, then keep it broken on newer versions. Users that can’t update to Maven 3.1+, for whether weird reason, can still use versioneye 2.0.1.

I’ve replaced Sonatype Aether with Eclipse Aether, declared prerequisite on Maven 3.1, cleaned up dependencies etc.