Fixed namespace issues in blog\Post::search()
Fixed versions summary pages in MySQL returning incorrect dates/authors
Hooks can now be defined in each app's conf/config.php

Each app's config can now have its own [Hooks] section, which makes it
easier to make hooks configurable via settings forms like the other
settings of an app.
Changed modifier API calls to POST requests, enabled folder deletion
Controller::require_acl() redirects back to original handler after login, and redirects to either /user/login or /admin depending on whether the 'admin' resource is included in the list.