Make base a regular stencil, simplify commands

[martinb3]

• simplify commandline to just show, list, or build. build is now an all-in-one create-or-update, fixes #68.
• base is now a regular stencil, just like the others. #69.
• shell.py now adds .decode('UTF-8') to all the fancy interrobangs and pizza symbols, to prevent ascii decode, fixes #71.
• add tests for metadata.rb template rendering, cookbook dir being created, etc