[shell-commands] an aggregate package for tools

The shell-commands package provides an aggregate bin directory of trampolines
that can be added to a shell $PATH in order to execute command line tools
from all built available packages.

Bug: PKG-54 #comment shell-commands package
Test: modified the rolldice package to contain a shell=true command and ran it from /pkgfs/packages/shell-commands/0/bin/rolldice.
Change-Id: Id691179a6f2b90a8f6e6d101c03f3924c88d6031
6 files changed