Consistent name and version for OOo RESTful LiveEdit plugin

Make sure the OOo extension carries an internal version number starting at 2.0.0 (because this is version2 of the LiveEdit framework) and that this version number is used in the end user generated files names:

nuxeo-liveedit-openoffice-extension-2.0.x.*

The version number should also be visible from within the user interface of OpenOffice or at least on the filesystem once the extension is installed.

The goal is to make it easy for the user to check that she has the right version of desktop extension installed.