Resolves Intellij issue 449

https://code.google.com/p/maven-android-plugin/issues/detail?id=449

Replaces all uses of Aether with maven-dependency-tree so we become agnostic about whether environment is Maven 3.0 or 3.1+

Android-Maven-Plugin project can now be built with either Maven 3.0 or 3.1+
Android projects can now be built with either Maven 3.0 or 3.1+
Tools that use the Maven-3.0 core (such as IntelliJ) will now work.

In doing this change I reverted maven.api.version back to 3.0.5 It might be possible to run with a newer version but I suspect not.

I also reverted the maven-testing.api.version to 2.1 which is the version that has a dep on maven-core-3.0. This could probably be moved forward again. It would just mean that the androidn-maven-plugin couldn't be built with maven-3.0

I came across one curio as part of this change. Line#483 of ProguardMojo explicitly handles commons-logging differently to every other library. And I can't see any good reason for it. Would love to get an explanation .. 

The change build cleanly and runs all the samples except the libraryproject instrumentation tests. But they weren't running before hand, so it's not a regression.