Add support for -force flag on builds [GH-119]
Add instructions for how to get Go set up to contribute.
Merge pull request #173 from jasonberanek/force-build

packer, builder/*: Add support for -force flag on builds [GH-119]
Update CHANGELOG
fmt
Merge pull request #176 from smerrill/better-contributor-notes

Add instructions on how to get Go set up to contribute.
Remove output directory in a step when "-force" flag step [GH-178]
Merge pull request #179 from jasonberanek/force-build

builder/virtualbox, vmware: Remove output directory in a step when "-force" flag step [GH-178]
buidler/virtualbox,vmware: only stat if not force

/cc @jasonberanek - Swapped this because why even bother doing a stat
if we're forcing anyways.
Expand VMware support to Workstation 9 (Linux).

The VMware builder should automatically pick between Fusion 5 and Workstation
9, based on which one is installed.
Missed a Mac/Linux incompatability

On the Mac ifconfig output is closer to "ip addr" in format, and so we need to
tweak the regex to work with the linux ifconfig output.  If Windows support is
to be added then this functionality may need to be pulled out into the driver.
Add support for CompactDisk and Headless

The driver has gained some new features, which we need to support.
Don't ignore tool finding errors

When looking for the vmrun and vmware-vdiskmanager tools, we were
actually ignoring the returned error.

Oops ... :$