Run two builds in parallel with go get.

By default, go get determines parallelism based on the number of
cores available. Those show up as 32 in the Travis CI environment
but a virtual machine is limited both by the amount of cores it
has allocated and the amount of memory available to it. 32 parallel
build processes are likely to exhaust the memory resources, leading
to killed processes.

This change reduces the number of builds running concurrently to 2,
which should reduce the likelihood of memory exhaustion greatly.

The number could probably be dialed up a little bit, but this should
give a good default reflecting the environment's resources.
Merge pull request #1486 from roidrage/master

Run two builds in parallel with go get
fixed vmware-vmx step order
Merge pull request #1497 from routelastresort/vmx-step-order

fixed vmware-vmx step order
builder/vmware-esxi: Ignore localhost for VNC lookup [GH-1480]

  Adds logic to ESXi driver VNC Address function to ignore listen
  addresses that bind to localhost (127.0.0.1), this allows certain
  default ports to be available on ESXi for VNC connections
website: document vmware-esxi VNC requirements
Merge pull request #1505 from jasonberanek/issue-1480

builder/vmware-esx: Ignore localhost for VNC lookup and document VNC requirements [GH-1480]