Moving to array_key_exists when adding plugin paths.
Merge pull request #481 from BGSU-LITS/master

Using array_key_exists when loading plugin paths
Use item_image_gallery() to use a default icon for non-image files.
Add and use a specific class for "Use HTML."

Fix #480.
Go back to using files_for_item() by default.
Fix #482, catch exception when guessing IM path.
Making sure that the plugin script directory is an array
Moving to isset to check for plugin directory
Merge pull request #484 from BGSU-LITS/master

Making sure the plugin script directories variable is an array.
Re-include upgrade message for superusers and admin.
Localize item citation and format date according to current Zend locale.
Update translation template for new strings.
Adjust width of search query input when advanced search is enabled.
Add 'human'=>'humans' to list of irregular words
add human to irregulars in Inflector in the other place
Remove rogue var_dump/die from theme config helper