manager: make lang-specific symbolic links relative
client: do not mount network shares with gvfs-smb anymore

Network shares will be implemented using autofs+cifs which solves the
two problems occurring with gvfs-smb+symlinks -hack:

 1) Symlinks were required because some applications (LibreOffice, etc.)
    did not know how to save documents to smb:// -locations (I/O errors
    occurred). Autofs+cifs avoids this because it makes mounts beneath
    the gvfs-layer. Moreover, gvfs-seemed to choke on symlinked
    smb-mounts by sending an enormous amount of QUERY_PATH_INFO
    requests.

 2) Autofs+cifs mounts will be done on-demand, i.e. when someone lists
    or enters the mount dir, gvfs-smb+symlinks required an excplicit
    activation.