Package Improvements

[RobiNino]

1. Change the output tree structure: a. Replace the 'id' field of every level with the 'id' field from the 'dependency' struct. b. Remove the 'dependency' struct in every level. c. Make the naming of fields on every level of the tree the same (currently the 'dependencies' in the first level are later called 'direct dependencies'.
2. Add an enhanced description on how to use the package output.
3. Support running the package from the command line.
4. Improve the tests coverage.
5. Consider changing the handling of JSON objects if a suitable unmarshalling package is found (one that can unmarshall complex types like Map<string, M<string, CustomStruct>>).