Adds local storage Boot support on PXE failures.

When used with partition image, adds capability to be able to
boot from local storage upon first PXE boot so that if subsequent
PXE boot fails, instances can still boot from local storage.

Change-Id: I4f412b604c1b21ef14c7e578851887fe7b7d0f7d
Merge "Adds local storage Boot support on PXE failures."