Use jna-0.1.1 and slf-4j.

Here we use the tagged version of jna instead of the snapshot. We also
remove all old usages of log4j and replace them by slf-4j.
Merge pull request #61 from agouge/jna-0.1.1

Use jna-0.1.1 and slf-4j

Here we use the tagged version of jna instead of the snapshot. We also
remove all old usages of log4j and replace them by slf-4j.

This should fix the failing build after agouge/java-network-analyzer#39.