A couple changes

This minor update basically adds the following:

1. Few @SuppressWarnings were added to get rid of some annoying compilation warnings
2. Added mark/unmark capability on any node in the graph. Marks can be default boolean flags, or any other Object can be associated with the node as a mark, which can be inspected on demand via method getMark.
3. Method get(node) was added to allow consumers to retrieve the exact node instance that was previously added to the graph.

Initial release

1.0

Merge branch 'master' of https://github.com/errodrigues/ez-graph