Added view helper to retrieve system contact email; added missing "unavailable" template to jquerymobile theme.

Implemented locale/time zone initialization; created placeholders for other resource initialization from 2.0alpha's application/bootstrap.php file.

Changed default authentication method to Database; this is the only option guaranteed to work in all contexts, so it is a safer default.

Moved themes from /themes/vufind/ to just /themes/ -- this simplifies file paths and fixes a bug in install.php that generated an invalid Apache configuration.  This increases the risk of conflict with themes from a different module, but using VuFind in combination with other theme-using modules is going to require extra customization anyway; not worth complicating the common use case.

When a variable is injected by the VuFind\Bootstrap process, it is only available to the layout; this revision modifies templates to access variables through the layout() helper so the correct values are accessible everywhere.

Made APPLICATION_ENV control detail level of error output; added detailed error message to 404 page.