Fix multi-repository startup issues

In a multi-repository setup there are a number of WARN logged which should not happen.

1. SuperSpace repository computation mixup in NavigationContextBean,

   2012-07-20 16:19:54,830 WARN  [org.nuxeo.ecm.core.api.localconfiguration.LocalConfigurationServiceImpl] Unable to retrieve local configuration for 'DocumentModelImpl(24876d62-c34c-4f39-bbbf-ff9b80b7271c, path=/, title=24876d
   62-c34c-4f39-bbbf-ff9b80b7271c)' and 'ThemeLocalConfiguration' facet: org.nuxeo.ecm.core.model.NoSuchDocumentException: No such document: 24876d62-c34c-4f39-bbbf-ff9b80b7271c
   

2. StartupHelper does not always navigate to the default repository and therefore doesn't find the user workspace:

   2012-07-20 16:01:03,535 WARN  [org.nuxeo.ecm.webapp.locale.LocaleStartup] Couldn't get locale from LocaleProvider, trying request locale and default locale
   org.nuxeo.ecm.core.api.ClientException: Unable to find root domain for UserWorkspace
           at org.nuxeo.ecm.platform.userworkspace.core.service.DefaultUserWorkspaceServiceImpl.computePathUserWorkspaceRoot(DefaultUserWorkspaceServiceImpl.java:85)
           at org.nuxeo.ecm.platform.userworkspace.core.service.DefaultUserWorkspaceServiceImpl.computePathForUserWorkspace(DefaultUserWorkspaceServiceImpl.java:97)
           at org.nuxeo.ecm.platform.userworkspace.core.service.DefaultUserWorkspaceServiceImpl.getCurrentUserPersonalWorkspace(DefaultUserWorkspaceServiceImpl.java:128)
           at org.nuxeo.ecm.platform.userworkspace.core.service.DefaultUserWorkspaceServiceImpl.getCurrentUserPersonalWorkspace(DefaultUserWorkspaceServiceImpl.java:119)
           at org.nuxeo.ecm.user.center.profile.UserProfileServiceImpl.getUserProfileDocument(UserProfileServiceImpl.java:53)
           at org.nuxeo.ecm.user.center.profile.localeProvider.UserLocaleProvider.getLocale(UserLocaleProvider.java:44)
           at org.nuxeo.ecm.webapp.locale.LocaleStartup.setupLocale(LocaleStartup.java:99)
           at org.nuxeo.ecm.webapp.locale.LocaleStartup.handleUserSessionStarted(LocaleStartup.java:79)
           ...
           at org.jboss.seam.core.Events.raiseEvent(Events.java:85)
           at org.nuxeo.ecm.webapp.helpers.StartupHelper.initServerAndFindStartupPage(StartupHelper.java:131)
           at org.nuxeo.ecm.webapp.helpers.StartupHelper.initDomainAndFindStartupPage(StartupHelper.java:170)
   

3. Repositories are not kept in the order with which they are registered.