Refactor to use fog-softlayer.

Adds support for:
* `knife softlayer vlan create`
* `knife softlayer vlan list`
* `knife softlayer vlan show <ID>`
* `knife softlayer datacenter list`
* `knife softlayer datacenter show <DC NAME>`
* `knife softlayer global ip list`
* Specifying public and private VLANs at bootstrap. `knife softlayer server create ... --vlan 12345 --private-vlan 67890`
* Specify image-id / template-id at bootstrap. `--image-id <UUID>`
* Specify no public network. [Automatically uses private IP as target SSH IP.]  `knife softlayer server create ... --private-network-only`

@ersteinmIBM, believe this has everything from #9 please let me know if I missed anything. (This was in the works when you opened #9. )

@underscorephil since this includes everything from #9 , #7 should be covered by this.

I'm going to merge this into master after I push the fixes to the tests that this broke (basically all of them).

Feel free to leave feedback here if I've missed anything or broken anything.