Extended context and user plug-in interfaces by missing call-back methods

The plug-in interface com.openexchange.admin.plugins.OXContextPluginInte rface was enhanced by
- changeCapabilities(Context, Set<String>, Set<String>, Set<String>, Credentials)
- changeQuota(Context, String, long, Credentials)


The plug-in interface com.openexchange.admin.plugins.OXUserPluginInterfa ce was enhanced by
- changeCapabilities(Context, User, Set<String>, Set<String>, Set<String>, Credentials)
- changeModuleAccess(Context, User, String, Credentials)
- changeModuleAccess(Context, User, UserModuleAccess, Credentials)