feat: add better shell-like command support

You can now execute any kind of program in the PATH.
You do, however, need to specify "./" if you want to execute a local
file, but that shouldn't be too big a problem.

scripts/wget-and-sci.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+# NOTE: This script assumes that the url is a .tar.gz file.
+# TODO: check if $# is >= 1 and give a warning that the extract dir should be provided.
+set -ex  # print all that we're doing (no need for echo's)
+tmpdir=$(mktemp -d)
+wget "$SCI_PIPELINE_URL" -P "$tmpdir"
+cd "$tmpdir"
+tar xf *.tar.gz
+cd $1
+sh .sci.sh
+cd -
+rm -rf "$tmpdir"