ECMS-6219: Unable to put > in css file

Fix description:
- Avoid the sanitization in CSS content
- Encode css data when rendering it as a file to avoid XSS attack
ECMS-6047 [IE] Can't drag and drop node with Icons mode

Fix description: Using correct global variable UISimpleView instead of UIListView.
ECMS-6265: SitesExplorer Tree disappears

Problem analysis
- Refreshing Explorer frame causes wrong updating current tab in Side Bar

Fix description
- Only refesh Explorer frame by ajax
ECMS-6229: ItemNotFoundException when opening Content Explorer after deleting a content in CLV

Fix descripiton:
- Remove all symlinks to deleted node before remove it
ECMS-6204: [IE8] Cannot add tag to web content

Problem analysis
- When an CKEditor is focus, it exists a reference to this object. In IE 7, IE 8, we cannot focus on another fields.
- Actual code uses the trim function which is not supported in IE 8

Fix description
- Destroy CKEditor objects when we do not need them.
- Use the trim function of jquery
ECMS-4880: Cannot go directly to a user folder with username as email address

Fix description:
- Remove @ as an illegal character in ECMS
Merge commit '7faa287b55004f41401accad6a4264dc4a139967' into HEAD