11297 guzzle bug

This branch adds a condition to the wcag_scheduler module so that if Guzzle isnt loaded it will attempt to load it.

To test
- Install Agov via drush. 
- Verify that Guzzle error doesnt occur. You may find that the WCAG module errors because it cant reach the web service or the web service cant reach your local site.

Note: The change to agov.install for line "'key' => 'agov_content_publication'," is fixing a typo.