Avoid a call to http://directory.unl.edu/service.php?format=json&uid=Anonymous

[gh-438] Handle cases where a non-url is passed in or if file_get_contents() returns NULL.  Also remove @ from a call as requested.

[gh-438] Replace file_get_contents with a wrapper (unl_url_get_contents) that will cache the results based on the requested URL's cache headers.

UNL fix applied to WBM 1.2 upgrade in commit 74670880
was mistakening placed inside if statement.

This reverts commit 59e92d58.

Readme updated to reflect that Trigger support is now included and a patch is no longer needed

Reduce dependency stack of rewrite map script to prevent hangs