Add tcpdump to our required package list in kvm-admin.

For now, we have to have tcpdump to do our automatic switch
configuration.  Until I pull this out of ohai and put it in its own
role, it needs to be in place before we tryt and run a kvm admin node.
Move Ethernet device speed finding to the Network cookbook.

This moves the code we use to detect what speeds an Ethernet device
supports out of ohai and in to the network cookbook.  This prevents
everyone from the additional network round trips that were potentially
needed to pull in the cstruct gem when we did not need it, and places
the speed detection code with its only user.

The speed detection code now also knows how to detect 2.5g, 20g and 40g
links for the proud owners of such exotic hardware.
Allow the Crowbar core to turn idle nodes off.

If a node has been fully discovered (or had its operating system
installed), we know how to turn it back on, and it has nothing else to
do, turn the node off.  The framework will turn the node back on when a
node role bound to it is committed.
add samba example
more details on SMB (move to another file next)
move parts of main install to subsection
move sledgehammer outside of main install
remove sledgehammer
reorganize
Update docker-admin.md
Update contributing.md
Update samba_cntlm.md
creating virtualbox instruction file
Update virtualbox.md
Update virtualbox.md
edits as requested
fix link
Refactor how we fetch gems and extra files.

This should cut down the amoutn of time we spend in Docker before
bringing up Crowbar, and have less churn in the future.

This also pulls in an updated Docker image.
Fix inadvertent boot loop from node powe off when idle code.
add more info including raw config to barclamp details