Create branch experimental-2.0
Adds Db action helper, Helpers resource to allow database access from controllers implementing Zend_Controller_Action.
Refactors installer form into its own Omeka_Form_Install form class that subclasses Omeka_Form.
Refs #377, adds Omeka_Login_Interface interface to allow for multiple login strategies (e.g. OpenID, LDAP).

* Adds Omeka_Login_Db as the default database implementation of Omeka_Login_Interface.
* Refactors UsersController and admin login form to make use of Omeka_Login_Db.
* Modifies login.css to account for the new div class="inputs" on the login form.
* Adds 'login' filter to UsersController::loginAction() to allow plugins to swap out the instance of Omeka_Login_Interface that is used for authentication.
* Refactors Currentuser resource to expect an integer as the identity returned by Zend_Auth::getIdentity().
Fixes UsersController to use the Db action helper.
Merges [4616-4674] from trunk to experimental-2.0.
Refs #734, converts ACL from a blacklist to a whitelist.

* Refactors record-based ACL conditions from the UsersController into a UserAccount assertion class.
* Refactors User model to implement Zend_Acl_Role_Interface and Zend_Acl_Resource_Interface.
* has_permission(): Refactors to allow passing Zend_Acl_Resource_Interface as the 1st argument.
* Modifies ACL definition to include the UserAccount assertion for specific User privileges.
* Adds a permissions check in the admin theme header for the current user.
* Refactors ACL definition (acl.php).
Refs #734, refactors Helper_Acl to avoid using thrown exceptions for control flow.
Merges trunk into experimental-2.0.
Merges trunk into experimental-2.0 branch.
Merges trunk into experimental-2.0 branch.
Removes deprecated Omeka_Db::getConnection().
Fixes ACL action helper to push the request to the login form if access denied AND no authenticated user.
Merges trunk into experimental-2.0 branch.
Merges trunk into experimental-2.0 branch.
Fixes error in ElementSetsController which does not use Db action helper correctly.
Merges trunk into experimental-2.0 branch.
Fixes a bug where not loaded plugin broker makes the login form barf.
Merges trunk into experimental-2.0 branch.
Merges trunk into experimental-2.0 branch.