Remove duplicate keys from nova.conf.

This fixes bug 1183531.

Change-Id: I35a5d8be8f5df6bcff522a5f6798430a7a1cb864
Document the requirement for heat-cfntools.

This addresses bug 1183195 in the short term.

Change-Id: Id6919aa444d253361ea6c07b452508d224f3d9db
Merge "Remove duplicate keys from nova.conf."
Merge "Document the requirement for heat-cfntools."