Issue #1822020: Doesn't respect 'access content' permission or node_access('view', ...) when displaying messages.

Issue #1822094: Add hook_admin_message_list_messages_alter() to modify messages shown in custom module.

Issue #1822114: Hide close link when user doesn't have permission (and move template prep to preprocess function)

Initial release of Admin message: Provides an easy way to show short messages to users. The messages can be individually closed by logged in users.