Makefile: Add `prove` to make test

Makefile

@@ -45,6 +45,7 @@ purge: uninstall
 
 test:
 	@if which git   > /dev/null; then :    ; else echo "'git' not found, exiting..."; exit 1;  fi
+	@if which prove > /dev/null; then prove; else echo "'prove' not found; not running tests"; fi
 
 moo:
 	@ which cowsay >/dev/null 2>&1 && cowsay "I hope you're happy now..."