This patch adds reading of vcpu count for instances, in preparation for
using the vcpu ratio in cluster scoring.

This also fixes other required node numbers.

Currently tryAlloc/tryReloc do not return the new instance, as this is
not needed for IAllocator alloc/reloc requests. However, for computing
the space, the new instance is useful, so we modify these functions to
return this information too.

The patch also improves hspace to have (with default parameters) a
parseable output.

This is a tool that checks how many instances (of same size, specified
by command line arguments) can be added to a cluster while remaining N+1
compliant.