assemble: apply choice of parallel or sequential build to tests
docker: fix locale
cart tests: move sequential build to end of test suite

sequential build is checked manually (for now)
sti: preserve installed packages between builds
cart tests: confirm tests passed before clean up

clearer output
save-artifacts: do not error when no installed packages
docker: don't remove haddock fields from package db

This will have to be done again very time a package is installed, may as well leave it as is.