Prepare next 2.5.0 version by deprecating few extensions

[thboileau]

Some extensions are marked as deprecated as it is planned to remove them in next 2.5.0 version.

• org.restlet.ext.emf
• org.restlet.ext.jaxrs (only old 1.1 version is supported)
• org.restlet.ext.oauth
• org.restlet.ext.openid
• org.restlet.ext.raml (only 0.8 version is supported)

extension org.restlet.ext.httpclient is no more marked as deprecated.