/cc @markpeek - The main thing is that the style for variables/methods
in Go is to use CamelCase (with the first letter generally downcased
unless an exported thing).

communicator/ssh: check scp codes and report errors

packer: builder name should be removed from rawConfig

This prevents the builder from rejecting the name (which it doesn't
know about) when validating the config.

The name isn't actually part of the builder config, so it should be
removed during parsing.

When there is an error returned from the Upload it is propagated back
to the main loop and may have additional log messages before the actual
error is displayed. This displays a log message close to where the error
actually occurred.

Currently file provisioners will silently fail when there is an error
with the remote side. This commit checks the scp error code and will
return the error message from the remote.

builder/vmware: fix Fusion DhcpLeasesPath

Now the VMware builder should automatically pick between Fusion 5 and
Workstation 9, based on which one is installed.

This unifies all the builders so that they all wait for SSH using a common
step available in builder/common. This common step has the best practices of
every previously unique step, such as retrying SSH handshakes, limiting
the number of SSH handshakes, timeouts, and so on.