Refactor tools and generator for better skeleton.json parsing

Lots of adjusts:

- readd node-optimist
- grao command args now can be --author-email instead of --author_email
  (note: swig doesn't allow dash in variable names, so for templates their names are adjusted)
- skeleton.json now has target, rewrites, ignores and conditions for better control of what will be generated
- commands now has appOnly option to only run inside an graoJS project
- commands now can configure prompt.properties to ask whatever they want
- commands now receive from tools the prompt instance and args - less code inside de commands
- generator now just generates; no prompt dependency.

TODO
- check --force (not working property) and... copy grao  to the app using de generator itself?