Add agms APN's for Truphone customer

Add "agms" APN for specific Truphone customer in USA and NL.

    <apn carrier="agms"
      mcc="310"
      mnc="280"
      apn="agms"
      type="default,supl"
  />

    <apn carrier="agms"
      mcc="204"
      mnc="65"
      apn="agms"
      type="default,supl"
  />

The settings have already been tested in a root phone by editing the file directly on the phones.