new module: chimi.settings

Currently contains global "noact" flag + DEFAULT_REPOSITORIES
core.py: corrected setting class attr. `repository' on pkg. definitions
command.py: add run-time option (-n) to set no-act flag.
incomplete support for uninitialized packages

i.e. packages which haven't even been fetched yet.  Still need to check
for uninitialized packages when user calls build/run/etc.
implemented use of `chimi.settings.noact' flag in core + command modules
unified "fetch" command with various methods of same name

To support that, also added "utility" as a proper package w/ definition,
etc.