Add dependency prettyPrint, visualization updates

This adds a prettyPrint method to the DependencyManager to enable
textual visualization of the TransformLikes that a DependencyManager
determines need to be run.

This also cleans up the GraphViz visualization with better edge
coloring and now uses the `name` method when labeling graphviz nodes.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@ibm.com>