Introducing ui-vdsm-hooks plugin

Using CGI scripts located on the host's web-server,
VDSM commands (vdsClient) can be invoked directly from the UI.

Added the following to Host context menu:
* GetAllTasks
* StopAllTasks
* ClearAllTasks
* GetStorageDomainsList
* GetConnectedStoragePool
* DisconnectStoragePool
* StopSPM
* VdsClient API - UI for all VdsClient API commands.

Blog post:
http://derezvir.blogspot.co.il/2013/06/ovirt-ui-vdsm-hooks-plugin.html

Change-Id: I1531e41eb87f33a7961a9d9ceb5f8a03c12a8cba
Signed-off-by: Daniel Erez <derez@redhat.com>