cli: atlasboard new package mypackage

[Iván Loire]

and atlasboard should create:

• a dashboards folder
• a widgets folder
• a jogs folder
• a README.md, with some basic generic info.
• a package.json file, with at least the name already populated.
• .gitignore??

[John Masson]

Issue #56 was marked as a duplicate of this issue.