Basic check for homedir permissions

Several guides suggest using data directories under your homedir,
rather than the default /opt area.  This is fine, but on RHEL6 and
similar distros homedirs are very restrictive 0700 permissions which
doesn't allow things like httpd to pass through to serve up files.

Even though stack.sh is taking over the host, changing permissions
automatically is not a nice idea.  So we just warn when it looks like
this is happening.

Change-Id: I9cd70e7fe90638a2a5c3b8fd94756afacac7c7be
diff --git a/stack.sh b/stack.sh
index 32a7d74..56ced5f 100755
--- a/stack.sh
+++ b/stack.sh
@@ -199,6 +199,9 @@
 sudo mkdir -p $DEST
 sudo chown -R $STACK_USER $DEST
 
+# a basic test for $DEST path permissions (fatal on error unless skipped)
+check_path_perm_sanity ${DEST}
+
 # Set ``OFFLINE`` to ``True`` to configure ``stack.sh`` to run cleanly without
 # Internet access. ``stack.sh`` must have been previously run with Internet
 # access to install prerequisites and fetch repositories.