Rename install.sh to setup.sh in order to take the Makefile targets.
Former make target names are now passed to the script like
$ ./setup.sh uninstall
Fixes#45.
New Plugins:
- bpkg-update: sync repo listings locally
- bpkg-list: list the repo names, with -d flag for details
- bpkg-utils: source-only shared utilities for bpkg plugins
Change-Id: I9ef04a86efa35c61cabd7c4ecfa7c7a134b41c6c