Update Ubuntu AMI's to latest
Update Ubuntu AMI's to latest

  + It looks like the ones we were using have been deregistered.

Signed-off-by: David Julia <ed0cc118a79fb117c6af81e058eba4f0ecd53e11@pivotal.io>

datachand/lattice,mikegehard/lattice,Klaudit/lattice,datachand/lattice,cloudfoundry-incubator/ltc,datachand/lattice,davidwadden/lattice-release,felipeg48/lattice,davidwadden/lattice-release,davidwadden/lattice,SrinivasChilveri/lattice,svrc-pivotal/lattice,mikegehard/lattice,Klaudit/lattice,datachand/lattice,Klaudit/lattice,felipeg48/lattice,Klaudit/lattice,svrc-pivotal/lattice,SrinivasChilveri/lattice,SrinivasChilveri/lattice,cloudfoundry-incubator/ltc,svrc-pivotal/lattice,davidwadden/lattice,SrinivasChilveri/lattice,svrc-pivotal/lattice