Added initial support for impersonation added

Conflicts:

	portlet/exoadmin/src/main/java/org/exoplatform/organization/webui/component/UIListUsers.java
	portlet/exoadmin/src/main/resources/locale/portlet/exoadmin/OrganizationPortlet_en.properties
	portlet/exoadmin/src/main/webapp/groovy/admintoolbar/webui/component/UIStarToolBarPortlet.gtmpl

Conflicts:

	portlet/exoadmin/src/main/java/org/exoplatform/organization/webui/component/UIListUsers.java
	web/portal/src/main/webapp/WEB-INF/web.xml
GTNPORTAL-3089 - added css files and impersonation icon
Added backup/restore of attributes to be cross-context aware. Removed SessionInvalidatorInterceptor from PC stack. Allow impersonation for disabled users.

Conflicts:

	pom.xml
	webui/portal/src/main/java/org/exoplatform/portal/application/PortalLogoutLifecycle.java
GTNPORTAL-2662 Impersonation in GateIn
GTNPORTAL-3245: Add comfriming when user remove permissions on edit page & site
GTNPORTAL-3370 - Added feature to restrict access to a node when outside publishing window

Added a new feature, to restrict access to a node if it's not inside of the publishing window.
This feature consists of:

* A new property (mixin) for the Node
* A new checkbox on the UI, close to the "publishing date" set of fields
* A new check on the UIPageActionListener, that displays the home page, should access to the node be restricted. This is so that the page has the same effect as of a "non existing node".