Add remove() to sysutils

This adds the remove() function, which works a lot like rm -rf - if you
remove() a file, it uses os.unlink, and if you remove() a directory it
uses shutils.rmtree().

src/pylorax/sysutils.py

@@ -135,3 +135,9 @@ def cpfile(src, dst):
         dst = joinpaths(dst, os.path.basename(src))
 
     return dst
+
+def remove(target):
+    if os.path.isdir(target):
+        shutil.rmtree(target)
+    else:
+        os.unlink(target)