Integrate Core Locking feature into nuxeo 5.

Basically add a Seam Action Listener that will :
 - provide methods to lock/unlock a document
 - provide methods to lock/unlock the current document (shortcut)
 - provide methods to lock/unlock a list of documents (see later, based on DocumentsListManager)

This AL should be conversation scoped.

1 - First step is to integrate actions lock/unlock on the currentDocument.
You will need to define a new action contribution and define guards on it.
 - document can be locked if user has write acces on the doc + doc is not locked
...
You may have to define methods on the ActionListener that will be called by the action system to check these guards.
Only add the action on non-folderish documents (DENY guard on Facet folderish)


2 - UI
- Integrate into the documents_tables a icon that indicates if a document is locked
- integrate into the summary view the information about lock :
  => if document is locked : display by who and til when

3 - FileManager integration
FileManager is used by the browser plugin and by the Office Plugin

for the Browser Plugin, the FileManager overwrite the document if a file with the same name is already present
=> should check before if document is not locked

for the Office plugin
the plugin ask to the FileManager for pre-edit actions and post-edit
=> lock should be available as pre-edit
=> unlock should be available as post-edit
Should also not render the LiveEdit link on documents that are locked :)