Fix maven resolver for certain packages.

The values specified in ArtifactDescriptorResult aren't sane in most ways. That is, they need evaluation & variable substitution.

I'm not sure why this was here in the first place, so this patch may be wrong. That is, I think the CollectRequest correctly returns direct dependencies as part of the query. Perhaps I'm missing something, so please tell me if something breaks with this approach.

I'd love to test this for buck itself, but I couldn't find a (direct) dependency list for it. Is there one somewhere?

Testing done:

buck run src/com/facebook/buck/maven:resolver -- /tmp/buck_repo/ thirdparty/jvm /tmp/mvn/ http://repo1.maven.org/maven2 io.netty:netty-all:4.0.24.Final

Before:

Exception in thread "main" org.eclipse.aether.resolution.DependencyResolutionException: Could not find artifact
io.netty:netty-tcnative:jar:${os.detected.classifier}:1.1.30.Fork2 in http://repo1.maven.org/maven2 (http://repo1.maven.org/maven2)
    at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveDependencies(DefaultRepositorySystem.java:384)
    at com.facebook.buck.maven.Resolver.getRunTimeTransitiveDeps(Resolver.java:435)
    at com.facebook.buck.maven.Resolver.resolve(Resolver.java:121)
    at com.facebook.buck.maven.Resolver.main(Resolver.java:482)
Caused by: org.eclipse.aether.resolution.ArtifactResolutionException: Could not find artifact io.netty:netty-tcnative:jar:${os.detected.classifier}:1.1.30.Fork2
in http://repo1.maven.org/maven2 (http://repo1.maven.org/maven2)
    at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:444)
    at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:246)
    at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveDependencies(DefaultRepositorySystem.java:367)
    ... 3 more
Caused by: org.eclipse.aether.transfer.ArtifactNotFoundException: Could not find artifact io.netty:netty-tcnative:jar:${os.detected.classifier}:1.1.30.Fork2 in
http://repo1.maven.org/maven2 (http://repo1.maven.org/maven2)
    at org.eclipse.aether.connector.basic.ArtifactTransportListener.transferFailed(ArtifactTransportListener.java:39)
    at org.eclipse.aether.connector.basic.BasicRepositoryConnector$TaskRunner.run(BasicRepositoryConnector.java:355)
    at org.eclipse.aether.util.concurrency.RunnableErrorForwarder$1.run(RunnableErrorForwarder.java:67)
    at org.eclipse.aether.connector.basic.BasicRepositoryConnector$DirectExecutor.execute(BasicRepositoryConnector.java:581)
    at org.eclipse.aether.connector.basic.BasicRepositoryConnector.get(BasicRepositoryConnector.java:249)
    at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:520)
    at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:421)
    ... 5 more

After: Works :)

This fixes #456 (closed) as well.