.service & fstab's noauto fixes

Hi, 

ldm is great, though I met some problems while installing it, especially with the provided systemd (v208 here)  service file. So here are my fixes / improvements : 

- now honours "noauto" in fstab
- .service file needed curly braces
- added support for BASE_MOUNTPOINT variable in config file (-p option) via
  .service file
- modified ExecStart according to the default Makefile target