[vSphere:] Implementation of Query for Guesttype and NICTypes

This pull request is a concept to implement a concept to query for guest types (fog: servertypes) and nic types (fog: interfacetypes).

Example on how to call:

compute.datacenters.first.servertypes.map{ | servertype | servertype.id }
=> ["windows8Server64Guest", "windows7Server64Guest", "winLonghorn64Guest", "winLonghornGuest", "winNetEnterprise64Guest", "winNetEnterpriseGuest", "winNetDatacenter64Guest", "winNetDatacenterGuest", "winNetStandard64Guest", "winNetStandardGuest", "winNetWebGuest", "winNetBusinessGuest", "windows8_64Guest", "windows8Guest", "windows7_64Guest", "windows7Guest", "winVista64Guest", "winVistaGuest", "winXPPro64Guest", "winXPProGuest", "win2000AdvServGuest", "win2000ServGuest", "win2000ProGuest", "winNTGuest", "win98Guest", "win95Guest", "win31Guest", "dosGuest", "rhel6_64Guest", "rhel6Guest", "rhel5_64Guest", "rhel5Guest", "rhel4_64Guest", "rhel4Guest", "rhel3_64Guest", "rhel3Guest", "rhel2Guest", "sles11_64Guest", "sles11Guest", "sles10_64Guest", "sles10Guest", "sles64Guest", "slesGuest", "centos64Guest", "centosGuest", "debian6_64Guest", "debian6Guest", "debian5_64Guest", "debian5Guest", "debian4_64Guest", "debian4Guest", "asianux4_64Guest", "asianux4Guest", "asianux3_64Guest", "asianux3Guest", "oesGuest", "oracleLinux64Guest", "oracleLinuxGuest", "ubuntu64Guest", "ubuntuGuest", "other26xLinux64Guest", "other26xLinuxGuest", "other24xLinux64Guest", "other24xLinuxGuest", "otherLinux64Guest", "otherLinuxGuest", "darwin11_64Guest", "darwin11Guest", "darwin10_64Guest", "darwin10Guest", "darwin64Guest", "darwinGuest", "freebsd64Guest", "freebsdGuest", "os2Guest", "netware6Guest", "netware5Guest", "solaris11_64Guest", "solaris10_64Guest", "solaris10Guest", "solaris9Guest", "solaris8Guest", "openServer6Guest", "openServer5Guest", "unixWare7Guest", "eComStation2Guest", "eComStationGuest", "otherGuest64", "otherGuest", "vmkernel5Guest", "vmkernelGuest"]

For specific nictypes:
compute.datacenters.first.servertypes.get("debian6Guest").interfacetypes
=>   <Fog::Compute::Vsphere::Interfacetypes
    [
      <Fog::Compute::Vsphere::Interfacetype
        id="VirtualE1000",
        name="VirtualE1000",
        datacenter="axref200",
        servertype="debian6Guest"
      >,
      <Fog::Compute::Vsphere::Interfacetype
        id="VirtualVmxnet3",
        name="VirtualVmxnet3",
        datacenter="axref200",
        servertype="debian6Guest"
      >
    ]
  >

For a specific nictype:

compute.datacenters.first.servertypes.get("debian6Guest").interfacetypes.get("VirtualE1000")
=>   <Fog::Compute::Vsphere::Interfacetype
    id="VirtualE1000",
    name="VirtualE1000",
    datacenter="axref200",
    servertype="debian6Guest"
  >

Please let me know what you think.

Thanks Marc.