Panda: Module Completion fallsback onto panda list

Use `panda list' for module completion when no projects.json is found
This both alows us to do completion prior to the user running
panda update|list|search|install and generates a projects.json for
future use. (note that panda list is significantly slower than parsing
the json ourselves).
Removed Obsolete Panda Notes.

Removed notes on panda module completion limitations
limitations were worked around by 4df9bd4