Add rustup script

rustup.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+set -e
+
+case $1 in
+    "prepare")
+        # FIXME Automatically detect latest nightly
+        read -p "Date of nightly to use (aka yesterday GMT): " TOOLCHAIN
+
+        echo "=> Installing new nightly"
+        rustup toolchain install --profile minimal nightly-${TOOLCHAIN} # Sanity check to see if the nightly exists
+        echo nightly-${TOOLCHAIN} > rust-toolchain
+
+        echo "=> Uninstalling all old nighlies"
+        for nightly in $(rustup toolchain list | grep nightly- | grep -v $TOOLCHAIN); do
+            rustup toolchain uninstall $nightly
+        done
+
+        ./clean_all.sh
+        ./prepare.sh
+        ;;
+    "commit")
+        git commit -m "$(rustc -V)"
+        ;;
+    *)
+        echo "Unknown command '$1'"
+        echo "Usage: ./rustup.sh prepare|commit"
+        ;;
+esac