NX-OS DME break in Path parsing

[remingtonc]

Path parsing e.g. /sys/intf/phys-[eth1/33] does not appropriately handle paths. Need to make Path parsing more modular to account for format differences that are not XPath based.

subscription {
  path {
    origin: "DME"
    elem {
      name: "sys"
    }
    elem {
      name: "intf"
    }
    elem {
      name: "phys-"
    }
    elem {
      key {
        key: "eth1"
        value: ""
      }
    }
  }
  mode: SAMPLE
  sample_interval: 10000000000
}

[remingtonc]

Tracking in nx-dme-path.